Absolute Value: A numbers distance from zero on a number line. The absolute value of -4 is 4 and 4 is 4.

Coordinate Construction: A method of locating points on an irregular-shaped object by plotting the three dimensions along the axes of the illustration

Coordinate Pair: Two coordinates that locate an exact location in 2D space by specifying the distance from the origin along the X axis and the distance from the origin along the Y axis.

Coordinate System: A two - or three- dimensional grid used in geometry and in CAD to locate points.

Cope: The upper portion of a flask used in molding.

Core: To form a hollow portion in a casting by using a dry-sand core or a green-sand core in a mold.

Core Point: In sand casting the box that holds a prepared mixture of sand and a binding substance.

Core print:A projection on a pattern that forms an opening in the sand to hold the end of a core.

Cotter pin: A split pin used as a fastener, usually to prevent a nut from unscrewing.

Counterbore: To enlarge an end of a hole cylindrically with a counterbore.

Countersink: To enlarge an end of a hole conically, usually with a countersink.

Contour interval: In map drafting, the distance between the contours.

Contour lines: Lines on a map that represent the elevations of the various portions.

Critical Extreme Position: A method of specifying the start and end points of a cam follower; this method is not concerned with how the motion path is achieved.

Critical Path Motion: A method of specifying the start and end points of a cam follower, as well as the path that the follower uses to get from the start point to the end point.

Cronaflex: A Du Pont trade name used to designate a polyester drafting film widely used as a drawing surface in technical illustration for use with both ink and plastic pencil.

Crop Marks Line: marks on an illustration to show the limits of the area to be reproduced. They are usually placed at each corner.

Cross Section: A drawing that shows and computes the amount of excavation that needs to be done to an embankment; the cross section is similar to the sectional views created for mechanical objects.

Crown: A raised contour, as on the surface of a pulley.

Current: The time rate of flow of electricity.

Current :A measure of how fast the electrons are flowing across a potential difference; measured in amperes.

Cursor: location coordinates The cursor coordinates that follow the standard Cartesian coordinate system. The lower left-hand corner of the drawing window is usually the origin, coordinate (0.0000,0.0000.

Cutting Plane: The plane through an object on which a sectional view is taken.

Cutting plane line: The line that represents the edge view if the cutting plane in the top view. Cutting plane lines are used to indicate the location of the cutting plane for section views, line of sight utilizing arrows, and identifies the section through the use of letters. The letters I,O,Q,S, X and Z are not used to identify sections .Graphically that are represented by a thick line .6mm line that is used in three different configurations: a series of evenly spaced dashes, alternate long dashes and pairs of short dashes, and the third the dashes are left out between the parts surface.

Cyanide: To surface-harden steel by heating in contact with a cyanide salt, followed by quenching.

Cylinder: A round shape that is similar to a pipe or a long round tube.

Cylinder: A single- curved surface with straight-line elements.

Cylinder Cam: A cam that is used to create transverse motion from a rotating object. As the cam rotates, the follower moves right and left.

Datum: A surface, line, or point that is known or assumed to be exact and is used as a point of reference for other dimensions. A theoretical point, line, area, or axis.

Dead Load: The weight of the actual building or structure.

Dedendum: The depth of the tooth below the pitch circle.

Depth auxiliary view: An auxiliary view named for the principal dimensions of the object shown in the auxiliary view.

Descriptive geometry: That branch of geometry that provides a graphical solution of a three-dimensional problem by means of projections upon mutually perpendicular planes.

Design drawing :A drawing that indicates the design, showing the general arrangement of the structure and giving specifics of the different members.

Detail drawing: A drawing that gives all of the information needed to construct a structural member having the components of necessary multi views, dimensional information, part and part number identity, part materials, engineering changes, drafter/checker names, assembly of parts and their quantity and general notes with manufacturing in information.

Detailed Thread Representation: The most realistic form of thread representation, but also the most complex, so it is not used except in special cases.

Detailing: The practice of using notes and dimensions to explain a technical drawing.

Details Drawings: in the architectural set that are drawn in a scale large enough to distinguish the small parts and features. detail drawings may be placed on sheets containing plans, elevations, and sections.

Development Drawing: of the surface of an object unfolded or rolled out on a plane.

Development: The layout of a pattern.

Diametric Pitch: Number of gear teeth per inch of pitch diameter.

Diazo:A copy made by exposing a sensitized paper and a translucent original drawing to both light and ammonia gas.

Diazo Paper:A reproduction paper that depends on light sensitivity and is developed by exposure to ammonia fumes or an aqueous solution.

Diazo-dry process: A reproduction process that uses paper coated with special chemicals. the image is developed by contact with ammonia vapors.

Die:A tool used to cut small external threads by hand.

Die: casting Process of forcing molten metal under pressure into metal dies or molds, producing a very accurate and smooth casting.

Die: stamping Process of cutting or forming a piece of sheet metal with a die.

Digitzer table: An input device. It insists of (1) a tablet that is a little larger than a notebook, (2) a plastic sheet that fits over the tablet and (3) a hand-held puck with several buttons. The tablet contains invisible spots that sense the position of the puck. each spot is programmed with a different CAD command.

Dimension Line: The line in a dimension that indicates the direction and extent of the dimension.

Dimension line: A line that has an arrowhead at each end indicating the extent of the dimension. A gap is left (except in architectural and structural drawing) near the middle for the dimension figure. On small drawings, dimension lines are spaced at least 3/8" (.375") from the object and at least 1/4" (.250") apart. the spacing must be uniform throughout the drawing.

Dimetric:An axonometric drawing in which two of the axes make equal angles with the plane of projection.

Dimetric Projection: A type of axonometric projection in which only two of the axes have the same scale and only two of the angles between the axes are equal.

Direction of revolution: The direction in which an object is revolved about the axis of revolution. The direction of revolution is clockwise or counterclockwise.

Displacement Diagram: A diagram that shows the path of a cam follower, including any rises, dwells, and drops.

Dividers: An instrument used for subdividing distances in which the spacing between the points is approximately 1" or over.

Dog: A small auxiliary clamp used to prevent work from rotating in relation to the face plate of a lathe.

Double-Line: Drawings Pipe drawings that show the outline of the pipe and the fittings in some detail; used mostly for catalogs and display drawings.

Dowel: A cylindrical pin, commonly used between two contacting flat surfaces to prevent sliding.

Draft: The tapered shape of the parts of a pattern to permit it to be easily withdrawn from the sand or, on a forging, to permit it to be easily withdrawn from the dies.

Drafting Film: A polyester film used as a drawing surface for ink and plastic pencil.

Drafting machine: A drafting tool that combines all the functions of the t-square, triangles, scales, and a protractor.

Drag: Lower portion of a flask used in molding.

Draw: To stretch or otherwise to deform metal.

Drawing Window: The large blank area in the middle of the screen of the computer monitor

Drill: To cut a cylindrical hole with a drill. A blind hole does not go through the piece.

Drill Press: A machine for drilling and other hole-forming operations.

Drop Forge: To form a piece while it is hot by forming it between dies in a drop hammer or with great pressure.

Dry mount: A heat-pressure process for fastening a drawing to mount board by laminating a thin sheet of shellac.

Dual Dimensioning: The practice of showing dimensions in two different measurement systems. The most common measurement systems for dual dimensions are U.S. customary (Imperial) and metric.

Edge View: A view of a plane surface obtained by looking parallel to a true length line in the surface.

Electric Circuit: A path from one side of a voltage source to another.

Electric Circuit: The path through which a current flows.

Electrical Drafting: The drawing of electrical wiring diagrams, interconnection diagrams, block diagrams, layout diagrams, and schematics.

Electrical drawing: Technical drawing used in the electronics industries.

Electricity: The flow of electrons from one point to another.

Electronics: The branch of electricity that involves the use of logic circuits and semiconductors.

Element: An imaginary straight line. For example, an element of a cylinder is an imaginary straight line on the surface parallel to the axis.

Elevation: A working drawing that shows vertical views of the exterior of a residential or commercial building.

Elevation: An outside view of a building.

Ellipse: A closed curve that is generated by a point moving in such a way that the sum of its distances from two fixed points is a constant.

Ellipse: A geometric form resembling a circle viewed at an angle.

Employability: The ability for someone to be employed; having those non technical skills that help a person get along and get ahead in the workplace, such as positive attitude, initiative, and teamwork.

Encoder: In CNC systems, the sensor that is used to determine the exact location of the axes.

Engineers scale: A scale with a series of scales in which inches are divided into 10, 20, 30, 40, 50, 60,or 80 parts.

Entities: Basic geometric shapes such as lines, circles, and arcs. These basic geometric shapes are called entities.

Erection diagram: A diagram that shows piece markings and indicates the sequence to be followed in the final assembly of the structure.

Exploded Assembly Drawing: An assembly drawing in which the various components are "exploded" or moved away from each other and connected using centerlines so that you can see how they are assembled.

Exploded Illustration: An illustration that shows each part of an assembly drawn separately and placed in a position that shows how the parts fit together

Extension line: A line that "extends" from the object ,with a gap of about 1/6"(.062")(.15mm) next to the object. It continues to about 1/8"(.125")(.3mm) beyond the outermost arrowhead. This line is used to indicate the point or line to which the dimension applies.

Extension Lines: The lines in a dimension that extend from the feature being dimensioned to the dimension line.

Extrusion: A 3D solid created by adding thickness to a 2D profile along a path or direction.

Eyeballing: Drawing a part approximately to shape and size using basic points as a guide - not guessing.

Face: To finish a surface at right angles, or nearly so, to the center line of rotation on a lathe.

Face Cam: A cam that has a follower that is perpendicular to the axis of rotation; also called a plate cam.

FAO: Finish all over.

Flask: In casting a two-part box that holds the sand. The upper part of the flask is called the cope. The lower part is called the drag.

Fastener: A general term for a variety of attachment devices, such as screws, bolts, nuts, washers, rivets, pins, and keys.

Feather key: A flat key sunk partly in a shaft and partly in a hub that permits the hub to slide lengthwise of the shaft.

Feature Control Frame: The frame that contains tolerances that control the shape and geometric characteristics of a feature.

Figure of intersection: The complete intersection between two solids.

File: To finish or smooth with a file.

Fillet:A curved radius on an inside corner of an object.

Fillet: A rounded inside corner on a casting.

Film Positive: A positive reproduction of black lines on photographic film.

Fin: See Flash

Finish mark: A symbol indicating that a surface is to be finished or machined.

Fit Degree: of tightness or looseness between two mating parts as a loose fit a snug fit or a tight fit.

Fixative: A clear solution, usually lacquer, that is sprayed on an illustration to protect lines or shading.

Fixture: A special device for holding the work in a machine tool, but not for guiding the cutting tool.

Flange: A relatively thin rim around a piece.

Flash: A thin extrusion of metal at the intersection of dies or sand molds.

Floor Plan: A working drawing that shows the arrangement of rooms, fixtures, and walls for a residential or commercial building.

Floppy diskettes: Transportable storage media for computer-generated information.

Flow line: A line used in exploded illustrations to show how a part is assembled with another part.

Flute: A groove as on twist drills, reamers, and taps.

Fly sketch: A method used by some illustration groups to show the breakdown of a subassembly, to enlarge an area, or to show alternate views by drawing a box or bracket around the parts.

Follower: A machine part that follows that shape of a cam to generate a specific motion.

Foreshortened Scales: Special scales used in dimetric and trimetric drawings. These scales are less than true size or foreshortened.

Foreshortening: The process of shortening lines and objects by proportionate amounts to give an illusion of depth or distance.

Forge: To force metal while it is hot, to take on a desired shape by hammering or pressing.

Forging: A metal shape produced by hammering heated bars or billets of metal between dies.

Foundation: A structure built to anchor a residential or commercial building and provide a solid, level base for it; can consist of walls or a slab.

Foundation Plan: A working drawing that shows the contractor exactly how the foundation of a building should be built.

Foundation planes: Plans that show the footings or the location of piles to be driven.

Framing: The construction of the rough structure of a building, including the floors, exterior and interior walls, stairs, and roof.

Friction Gear: A gear that, if placed in contact with another friction gear and rotated, will transmit motion to the other gear.

Frisket Paper: A thin paper used to cover portions of art during airbrushing

Front View or Front Elevation: A view that shows the true width and height of the house, but not the depth. The view is obtained by extending perpendicular projectors from all points on the house to the plane.

Full Section: A sectional view obtained by passing a cutting plane fully through the object.

Function Keys: The keys labeled <F1> through <F12>. They are shortcut keys. They issue commands with the push of a button.

Galvanize: To cover a surface with a thin layer of molten alloy, composed mainly of zinc, to prevent rusting.

Gasket: A thin piece of rubber, metal, or some other material, placed between surfaces to make a tight joint.

Gate: The opening in a sand mold at the bottom of the spur through which the molten metal passes to enter the cavity or mold.

Gate Valves: Valves that have tapered plate, or gate, that rises to allow full flow and lowers to block the flow.

Gear: A device that transfers rotary motion.

Gear Ratio: A calculation that is used to determine the rotation of gears in a gear train.

General Assembly: A drawing that shows how the parts fit together and how the assembly functions.

Geometric Dimensioning and Tolerancing (GD&T): A dimensioning and tolerancing technique that controls the shape and geometric characteristics of a feature, showing acceptable deviations for the form, profile, orientation, location, and run out of a feature.

Giant Bow Compass: A large bow compass with a maximum radius about equal to that of a conventional large compass, but with the rigidity of the small bow instrument.

Girt's: Horizontal framing members that span between posts to support the exterior siding on a building.

Globe Valves: Valves that have a spring-loaded disc to provide a seal. They are used to regulate both flow and pressure in a pipe.

Glossy Paper: A type of photographic print with black lines on a glossy surface.

Grade: The measurement found by the following formula: Percent Grade = Vertical distance / Horizontal distance X 100

Graduate: To set off accurate divisions on a scale or dial.

Graphic Symbols: Symbols used to simplify presentation of electrical devices. These symbols have been standardized by the American National Standards Institute. The are referred to by the electrical drafter before drawing any electrical diagrams.

Grind: To remove metal by means of an abrasive wheel, often made of carborundum. Used chiefly where accuracy is required.

Grips: The small, colored squares that appear at key points on a selected object in AutoCAD. Grips allow you to edit objects informally by selecting and moving individual points.

Groove Cam: A cam in which a groove is manufactured into the face to retain the follower and kept it in close contact with the cam.

Group: A named selection set of objects

Half-Section: The section obtained if the cutting plane is passed only halfway through an object and then the quarter of the object in front of the cutting lane is removed.

Halftone: A method of simulating continuous tone by photographing a drawing with the use of a screen with dots to obtain variable density.

Half-View: A view sometimes used for simple symmetrical objects. Center lines instead of break lines are used to limit the half views.

Hand Drawing: A drawing created by hand, usually by using traditional drafting instruments such as a T-square and triangles.

Hard Disk: The primary storage medium in a computer. Hard disks are measured by their size in bytes and by their speed in milliseconds. Hard disks range in size from tens of megabytes to several gigabytes. The speed of a drive is a measure of how fast you can read or write information to the drive.

Harden: To heat steel above a critical temperature and then quench in water or oil.

Hatch Pattern: A pattern of lines that is used to show cut surfaces in a sectional view.

Heat-Treat:To change the properties of metals by heating and then cooling.

Height Auxiliary View: An auxiliary view that shows the principal dimension, height.

Helix: The design made by screw threads as they wind around a shaft in a curve.

Hidden Lines: Dashed lines that show the hidden edges or contours of a part. Hidden lines are used to show invisible parts that otherwise could not be shown at all. Hidden lines should always touch the visible line representing the edge where the hidden feature starts or ends. Hidden lines may be omitted from drawings for clarity purposes.

Hole Table: A system of tabular dimensions used to locate holes in a plate.

Hydraulic System: A system in which pressurized fluids drive actuators and motors.

Illustration Board: A stiff cardboard paper material of several layers with a smooth side that is used as a drawing surface.

Inclined Plane: A flat surface that is not parallel or perpendicular to the X, Y, or Z axis

Index Number: A number or letter assigned to identify a part on an illustration and keyed to a parts lists that describes the part.

Integrated Manufacturing: That type of manufacturing that integrates CAD with manufacturing process

Interchangeable Part: Refers to a part made to limit dimensions so that it will fit any mating part similarly manufactured.

Intermediate: A reproduction of a drawing on translucent paper or film. It is used instead of the original drawing to reproduce other prints.

Interpolation: In CONC. control systems, a mathematical model to determine the best-fitting path to approximate locations and the most efficient speeds for the operation

Involute: A curved profile that is generated by establishing a fixed point and generating a curve path from it. The involute is among the most effective shapes for gear teeth

Involute System: The most widely used gear tooth form in use today.

IPB: Illustrated parts breakdown abbreviation

Irregular, or French, curves: Curves made of amber or clear plastic used to draw irregular curves.

ISO: International Standards Organization; produces internationally recognized drafting standards.

Isocircle:; An ellipse that shows how a circle would look when shown in an isometric view.

Isometric: An axonometric drawing with all the axes at equal angles to the plane of projection. Isometric is the most frequently used method in technical illustration.

Isometric Assembly Drawing: An assembly drawing that shows an isometric view of the objects and contains small notes called balloons to indicate find numbers associated with the parts list of an assembly.

Isometric Drawing: A drawing prepared so that the front edge (and those edges parallel to it) will appear vertical. The two lower edges (and those parallel to them) will appear about 30* with horizontal.

Isometric Lines: Lines that are parallel to the axes.

Isometric Pipe Drawing: A pipe drawing that shows a pictorial view of the piping system from an angle so that the viewer can picture the system in three dimensions.

Isometric Projection: An axonometric projection in which all the axes are at 120* to each other and the scales on all the axes are equal.

Isoplane: Any of the three isometric planes in AutoCAD

Iteration: A return to a pervious step of the design process for alterations; in general, a version of a design or idea.

Ithography: A process of printing from a plane surface based on the mutual repulsion of water and grease

Jig: A device for guiding a tool in cutting a piece. Usually it holds the work in position.

Joints:L In truss construction, the points at which the parts of a truss connect.

Journal: Portion of a rotating shaft supported by a bearing.

Kerf: Grove or cut made by a saw

Key: A small piece of metal sunk partly into both shaft and hub to prevent rotation.

Keyboard: The most common input device. It consists of typewriter keys, navigation keys, function keys, and a number keypad

Key seat: A slot or recess in a shaft to hold a key.

Key way: A slot in a hub or portion surrounding a shaft to receive a key.

Knurl: To impress a pattern of dents in a turned surface with a knurling tool to produce a better hand grip.

Lap: To produce a very accurate finish by sliding contact with a lap, or piece of wood, leather, or soft metal impregnated with abrasive powder.

Lathe: A machine used to shape metal or other materials by rotating against a tool.

Layout: An accurate plan of an illustration showing easily understood views and proper placement of parts with index numbers, leaders, and callouts to clearly identify the object.

Layout: The arrangement of views on a technical drawing.

Layout Drawing: An assembly drawing made to scale and including the views necessary to show the size and shape of each part. Dimensions are omitted.

Lead: The distance , parallel to the axis, from a point on one turn of the helix to the corresponding point on the next turn

Leader line: A line the extends from a part or object. It is used to identify the part by showing an index number or letter at one end of the leader. Graphically they are thin .3mm lines ending with an arrowhead. A short horizontal shoulder may extend from the leader at mid letter height and must start from the first or last letter or number of the note. Leaders should never be horizontal or vertical.

Leader: A line with an arrow at one end and a hook (horizontal bar) on the other end; used to refer note text to a specific part or area of a drawing.

Leader: A thin solid line that "leads" from a note or dimension. It is terminated by an arrowhead touching the part to which attention is directed.

Legend: An explanation of symbols or notes that appear on an illustration

Lettering: Devices Instruments used with a special guide or template to form letters.

Line Chart: A chart on which numbers plotted on a grid are connected by straight lines

Line Illustration: A technical illustration made only with lines. It contains no tonal shading.

Line of Intersection: The point at which two surfaces intersect.

Linear Dimensions: Dimensions that specify horizontal and vertical distances.

Linear Hole Patterns: Hole patterns used when the holes are dimensioned the same way for mating parts to ensure consistency among the holes.

Line types: The various types of lines used to show different things on a technical or multi view drawing. For example, a thing, dashed line type represents a hidden line.

Live Load: Temporary loads a building or structure might need to withstand, such as snow or traffic.

Lowercase Letters: Letters that are not capital letters. They are called lowercase because they are kept by compositors in the lower case of type

Lug: An irregular projection of metal, but not found as in the case of a boss, usually with a hole in it for a bolt or screw.

Machine Drawing: Technical drawing used in the manufacturing industries.

Machine Tool Tolerance: A measure of accuracy and repeatability in both manually operated and numerically controlled systems.

Machine Tools: The machines and devices that are used to remove, add, or form material in the manufacturing process.

Major Axis: The long axis of a shape (as an ellipse)

Malleable casting: A casting that has been made less brittle and tougher by annealing.

Map: A drawing of the earth's surface or a part of it.

Marine Drawing: Technical drawing use din ship construction. Some industries use the term drafting instead of technical drawing.

Mass Properties: Properties of an object, including mass (assuming a density of 1.0), volume, bounding box, centroid, moments of inertia, products of inertia, radii or gyration, principal moments and X-Y-Z directions about the centroid.

Mat: A frame of paper of cardboard used in mounting completed illustrations

Material Conditions: Modifiers that change a tolerance with respect to how much material is present in a geometric feature.

Material Safety Data Sheet: A formal document that specifies any hazards or precautions associated with a chemical or other product.

Mating Dimensions: Certain dimensions must correspond to make the parts fit together.

Mating Parts: Two or more parts that fit together.

Mechanical Drawing: A drawing made with precision drawing instruments.

Members: In truss construction, the various parts of a truss.

Metallic-Insert Gas: A method of gas-shielded welding in which a reel of welding wire is fed into the weld zone while the weld is formed.

Metric System: A decimal system of measurement.

Microfilming: A photographic process that reduces drawings and records to their original size.

Micrometer Caliper: A precision measuring instrument that allows measurements to four decimal places.

Mill: To remove material by means of a rotating cutter on a milling machine.

Minor Axis: The short axis of a shape (as an ellipse)

Model Space: The space in AutoCAD in which almost all drawing geometry is created.

Modeling: The process of creating full-size 3D objects in a CAD file.

Mold: The mass of sand or other material that forms the cavity into which molten metal is poured.

Mounting: The process of placing an illustration on a stiff cardboard backing, usually with a heavy brown paper covering over a thin tissue-paper cover that protects the illustration from damage

Mouse :An input device. It has a rubber ball on the bottom that rolls on the desktop. When you move the mouse up or down, the cursor on the screen moves up or down.

MS: An abbreviation for military specification

MS: Machinery steel, sometimes called mild steel with a small percentage of carbon. Cannot be hardened.

Multi view Drawing: A technical drawing that incorporates more than one view of an object in order to describe it completely.

Mylar: A Du Pont trade name for polyester film used as a drawing surface in technical illustration.

NAF: An abbreviation for National Aircraft Standards. A method for designating standard parts on blueprints.

NAS:An abbreviation for National Aircraft Factory. A method for designating standard parts on blueprints.

Navigation Keys: The keys that move the cursor around the monitor screen.

Neck: To cut a groove called a neck around a cylindrical piece.

Needle Valves: Valves that use precisely tapered needle to seal the flow. When the valve handle is turned, the needle moves away from the seat, allowing precise flow and pressure control

. Negative: A reverse-reading background copy with white lines on paper or film and a black background. Used for printing a positive.

Non analytic Surface: A surface that is formed from a given set of data points or curves that are used as control points for the surface.

Non-Isometric Lines: Lines that are not parallel to the axes

Normalize: To heat steel above its critical temperature and then to cool it in air.

Noun/Verb Selection: The process of selecting objects in AutoCAD using grips and then entering a command to be used on the selected objects.

NURBS Non-uniform rational B-spline; the method AutoCAD uses to calculate sp lines.

Object Linking and Embedding: A Windows feature that allows you to link a copy of an external document to an AutoCAD file or to embed a copy of the external document into the AutoCAD file. Linked documents can be updated automatically, but embedded documents are a static instance of the original file and cannot be updated.

Oblique Projection: A projection in which the X and Y axes are parallel to the viewing plane and the Z axis is at any angle other than 90*

Offset Section: A section in which the cutting plane is bent or "offset" to pass through several features of an object that are not in a straight line.

Ohm: The unit in which resistance is measured.

Ohm's Law: A set of equations that describe the relationship among current, voltage, and resistance in an electric circuit.

One-Point Perspective: A perspective sketch with one vanishing point.

Open-Loop System: A system that uses impulses or signals to determine where the tool is on a computer-controlled machine.

Operating System: The system that translates the commands from the CAD software program into language the computer hardware can understand.

Operators: In math, the symbols that tell you what operations to perform on a number. In AutoCAD's Boolean commands, the operators determine what operations will be performed on the selected solids.

Ordinate Dimensions: A series of linear dimensions in which one end of each dimension is located at a single specified datum.

Origin: The point on a Cartesian coordinate system at which the X and Y axes cross.

Orthogonal Views: The six principal views that can be included in a multi view drawing of a mechanical object, except the normal views are called plan, elevation, and side elevation views.

Orthographic: A multi view drawing in two dimensions rather than three, requiring several "flat" views to show the characteristic of an object.

Orthographic Projection: The process of creating views of an object by projection multiple views from the object and considering what an observe would see if looking from each direction.

Outline Assembly: A drawing that shows one or more views of an assembly "in outline". Little or no sectioning is generally needed. Unimportant details are emitted.

Outside Spring Calipers: Calipers used to check the nominal size of outside diameters.

Pad: A slight projection, usually to provide a bearing surface around one or more holes.

Pagination: A term used in preparation of parts catalogs. It involves the arranging of illustrations and text in proper sequence to best utilize available space.

Paper Space: The space in AutoCAD in which multiple views of an object can be laid out on a border and title block for printing.

Parallel Circuit: A circuit that contains components that are connected to separate legs of the circuit in such a way that if one component fails, the others still work

.Parallel Ruling Straightedge: A straightedge controlled by a system of cords and pulleys. These permit it to be moved up or down on the board, always maintaining a true horizontal position.

Parallel-line Development: A rectangular pattern such as the type produced when a prism or cylinder is rolled out.

Partial View: A view that gives a complete shape description, while also omitting the drawing of difficult curves.

Parts List: A bill of material; a record of all of the discrete components or parts that make up an assembly or finished product.

Paste-Up: The work involved in preparing a finished illustration for reproduction. It includes applying index numbers, callouts, and leaders and mounting and covering.

Path On: a CNC machine, the route along which the tool or cutter travels. The path is chosen by the computer and is usually very simple.

Pattern: A form or model used as a guide or imitation for producing parts and products.

Pattern: A model, usually of wood, used informing a mold for a casting. In sheet metal work a pattern is called a development.

Pattern Development: The production of flat patterns for use in creating products

Pattern Drawing: A drawing that gives only the information needed in the pattern shop.

Peen: To hammer into shape with a ball-peen hammer.

Penetrant: The dye that is used in penetrant testing to show any surface defects that may be present.

Perspective: The technique of resenting objects so that they appear progressively smaller as they are farther away.

Perspective: Keeping things in a drawing sized relatively to each other.

Perspective Drawing: A three-dimensional drawing that shows an object as the eye sees it from one particular point

Parallel: lines converge at an vanishing point.

Perspective Projection: A projection in which the projection lines converge at one or more vanishing points.

PERT: An abbreviation for Program Evaluation Review Techniques, usually charts.

Phantom: A stimulated transparent surface through which normally hidden parts can be seen. An x-ray view.

Photocopying: A commercial contact method for reproducing drawings.

Pickle: To clean forgings or castings in diluted sulfuric acid.

Pictograph: A graph or chart in which pictures are used as symbols to represent units or quantities.

Pictorial Drawings: Two-dimensional drawings that make objects appear to be three-dimensional. The three basic types of pictorial drawings are axonometric, oblique, and perspective drawings.

Pictorial Drawings: One in which the object is viewed in such a position that several faces appear in a single view.

Pie Chart: A chart that shows how the whole is split up into portions.

Piercing Point: The point of intersection of a line and an oblique plane.

Piles: Structural pillars that are driven deep into soil or bedrock to help support a building or structure.

Pinch Valve: A valve that consists of a threaded clamp that is placed around flexible tubing. The clamp is tightened to block off flow and released to allow flow.

Pinion: The smaller of two mating gears.

Pipe Fittings: Pieces that are used between two pipes to connect the pipes.

Pitch: (of thread) The distance, parallel to the axis, from a point on one thread to the corresponding point on the next adjoining thread.

Pitch Circle: An imaginary circle corresponding to the circumference of the friction gear from which the spur gear was derived.

Pixels: Dots displayed on the screen of a monitor.

Plane: To remove material by means of a planer.

Planish: To impart a planished surface to sheet metal by hammering with a smooth-surfaced hammer.

Plans: The most important part of the architectural drawings. They contain most of the information and show more of the dimensions than do the elevations. What we call plan is in reality a horizontal section through the house taken above the window-sill height.

Plastic Pencil: A non graphite pencil used for drawing on drafting film.

Plastic Templates: Time-saving devices available for drawing symbols such as electrical symbols.

Plastic Welding: A welding process in which electrodes produce a high-frequency vibration that creates friction, causing the plastics to heat up and soften. The softened plastics fuse at the point of contact with electrodes.

Plat: (or plot) A map of a small "parcel" of land.

Plate: To coat a metal piece with another metal, such as chrome or nickel, by electrochemical methods.

Platform Framing: Construction in which each floor is built as a platform on top of the floor below it, starting at the foundation.

Plotting: The process of drawing every line, curve, and letter using an ink pen or pencil point mounted in a mechanical device called a plotter. Plotting is done on a plotter.

Pneumatic System: a system in which pressurized air is used to drive actuators, rotate air-driven motors, or open and close valves.

Point-to-point Control: A CNC control system that gives the operator limited control over the path between the points specified in the program.

Polar Array: An array of object at equal intervals in a circular manner around a central point.

Polar Dimensioning: A method of locating holes on a bolt circle by giving the diameter of the bolt circle and an angle.

Polish: To produce a highly finished or polished surface by friction, using a very fine abrasive.

Polygon: A closed object that has at least three sides.

Polyline: An AutoCAD object that is composed of one or more line or arc segments.

Positive: A print normally made with a negative resulting in dark lines on a light background.

Post-and-Beam Framing: Construction in which a system of widely spaced posts are joined by heavy beams to form the skeleton of the building.

Power: A measure of the rate at which work is done or the rate at which electric energy is used by a circuit.

Primary Auxiliary Views: The three types of ordinary auxiliary view - the depth auxiliary, height auxiliary, and width auxiliary views.

Primitives: Basic 3D objects that can be used as a starting point for more advanced models.

Prism: An object used to refract or disperse a beam of light.

Prism: A geometric shape having plane faces parallel to an imaginary axis.

Process and Instrumentation Drawing :A pipe layout drawing that shows that contractor where to install the various pipes, specifies the type of pipe required, and indicates where the process and in-line components need to be located.

Process Sheet: A diagram or list that shows a logical sequence of events for each process in manufacturing a given part or assembly.

Production Illustration: An illustration that shows the way parts fit together and the sequence of operations to be performed.

Professional Engineer: An engineer who has completed four years of education from a nationally accredited engineering program, has documented experience, and has passed the licensing tests in the state in which he or she practice.

Profile: To cut any desired outline by moving a small rotating cutter, usually with a master template as a guide.

Proportion: The relation in size between the various parts of a drawing. A drawing is said to be in proportion if all its parts are the correct sizes when compared to all the other parts.

Punch: To cut an opening of a desired shape with a rigid tool having the same shape, by pressing the tool through the work.

Pyramid:A four-sided, triangle-shaped object in which the sides slope into a point.

Pyramid: A geometric shape having plane triangular faces that intersect it at a common point.

Quadrilateral: A geometric shape having four sides.

Quality Control: A system to help ensure that the product being manufactured complies with the specifications each and every time it is produces.

Quench: To immerse a heated piece of metal in water or oil in order to harden it.

Rack: A flat bar with gear teeth in a straight line to engage with teeth in a gear.

Rack and Pinion: A device that transfers rotary motion. The pinion (gear) rotates, causing the rack to move forward and back.

Radial-Line Development: A development in which the edges or elements "radiate" like spokes in a wheel from a point, instead of being parallel. These lines usually do not show true length in the regular views.

Random Access Memory:(RAM) Computer memory that is stored on integrated circuit chips

Rapid Prototyping: The process of creating a physical 3D model that can be used to explain a concept or casting pattern before the component is actually manufactured.

Ream: To enlarge a finished hole slightly to give it greater accuracy, with a reamer.

Rectangular Array: An array in which the objects are arranged in rows and columns.

Reference Dimensions: Dimensions provided on a drawing to provide information only. They cannot be used for inspection measurements.

Region: In AutoCAD, a two-dimensional, closed object that can be created from other 2D objects, including lines, circles, arcs, ellipses, and elliptical arcs.

Register:The placing of lines on the boarder of a drawing. The lines are for aligning overlay sheets

Regular Solid: A geometric shape with faces that are regular polygons

. Relief: An offset of surfaces to provide clearance for machining.

Removed Section: A section that is moved from its normal position to some more convenient position on the sheet. In such cases, the removed section may be drawn to a larger scale if desired.

Rendering: Usually refers to shading an illustration so that it will give a lifelike appearance. Various means such as pencil, link, colors, and commercial paste-up material are used. Sometimes the word indicates any type of three-dimensional drawing.

Rendering: A method of showing a realistic view of an object; similar to shading, but rendering is more complex and yields a better result.

Resistance: The amount of opposition against an electric flow between two points; measured in ohms.

Resistance: The opposition to the flow of electricity.

Resistance Welding: A welding process that combines electricity and heat to create the weld.

Resolution: The quality of display of a monitor screen.

Retouching: The process of applying various gray, white, and black shades to a photograph or illustratio