3MFModern 3D manufacturing format that can carry mesh geometry plus richer manufacturing metadata.AnisotropyDirection-dependent material behavior, common in fiber-reinforced plastics and layer-based additive manufacturing.Basic dimensionA theoretically exact dimension used with geometric tolerancing to define location, orientation or profile.Bend allowanceThe arc length of the neutral axis through a sheet-metal bend, used in flat-pattern calculation.BossA local protruding feature, commonly cylindrical, used for fasteners, locating or mounting.Clearance fitA fit where the smallest hole remains larger than the largest shaft across the specified limits.Cold runnerAn injection-molding runner system in which feed material solidifies and is typically ejected with the molded part.DatumA theoretically exact reference used to establish measurement or geometric control in GD&T.Design intentThe relationships and constraints that make a CAD model respond correctly to expected design changes.Draft angleA taper relative to the mold pull direction that helps a molded part release from tooling.Ejector pinA mold component that pushes a cooled molded part away from the core or cavity during ejection.Feature treeThe ordered sequence of parametric CAD features and references used to build a model.GateThe controlled entry point through which molten polymer enters an injection-mold cavity.IGESOlder neutral CAD exchange format historically used for curves and surfaces.InfillInternal printed structure used in many FDM parts to reduce mass, time and material.Interference fitA fit where the largest hole remains smaller than the smallest shaft across the specified limits.K-factorA sheet-metal parameter describing the neutral-axis location through thickness during bending.KerfMaterial width removed by a cutting process such as laser, plasma, saw or waterjet cutting.LMCLeast material condition — the size state containing the least amount of material for a feature of size.Layer heightThe vertical thickness of each deposited or cured layer in additive manufacturing.Living hingeA thin flexible molded section designed to bend repeatedly while connecting two regions of the same part.MMCMaximum material condition — the size state containing the greatest amount of material for a feature of size.Parting lineThe boundary where mold halves meet and separate.Press fitAn interference assembly where elastic/plastic deformation creates retention between mating components.Profile toleranceA GD&T control that defines a tolerance zone around a true profile.RSS toleranceA statistical root-sum-square estimate for combining independent centered tolerance contributors.RibA thin reinforcing wall used to increase stiffness without making the entire section thick.RunoutA geometric control that limits variation of a surface as a part rotates about a datum axis.STEPISO 10303-based neutral product-data exchange format widely used for CAD geometry transfer.STLTriangle-mesh format commonly used for additive manufacturing and visualization.ShrinkageDimensional contraction between processing and final stabilized part condition.Shut-offMating tool surfaces that close against each other to form an opening, slot or boundary without a separate core.Sink markA local surface depression caused by differential shrinkage, often above thick molded regions.Support structureTemporary geometry used to support overhangs or process constraints during additive manufacturing.Tolerance stack-upThe combined dimensional variation of multiple features along a functional chain.Transition fitA fit whose tolerance limits allow either clearance or interference.UndercutGeometry that mechanically prevents straight-line removal from a tool or assembly direction.WarpageUnwanted shape distortion resulting from nonuniform shrinkage, cooling, stress or material orientation.Watertight modelA closed geometric representation without open boundaries that encloses a volume.Worst-case toleranceA stack method that assumes all contributing dimensions simultaneously reach their most unfavorable limits.