Concavity n: Negative (inward) curvature. A depression in a surface.

Cone v: To taper a surface by increasing the curvature of its cross-section over its length.

Coning a: Describing the tapering of surface or highlights.

A Coning Surface

Coning allows a surface to transition smoothly from a tight cross-section to a more relaxed one. Highlights will dissipate over the surface toward the relaxed end, and gather toward the tight end, giving tension and movement to the surface.

Convex a: Having positive (outward) curvature.

Convexity n: Positive (outward) curvature. A bulge in a surface.

Crease n: A sharp, shallow edge where two surfaces meet.

Crown n: A shallow convexity of surface. v: To add convexity to a surface.

Cut-line n: The break between two flush surfaces. A division between two panels.

Dimple n: a distinct, concave surface depressed into a convex or shallower concave surface, delineated with a hard intersection. Opposite of blister. v: to depress a crisply delineated area of concavity into a surface.

Edge n: The corner formed by two surfaces meeting at a positive angle without a transitional surface.

Extrusion n: A shape with a constant cross-section. (also known as a Drag Section)

Fillet n: A concave surface which acts as a tangential transition between two intersecting surfaces. v: To smoothly transition two or more surfaces which meet at a negative angle.

Flush a: Describing two or more unconnected surfaces that share the same plane.

Hollow a: To have shallow concavity; or, in the case of a convex surface, to appear, in the context of the surrounding shapes, to have concavity.

Lathe n: A shape with a radially constant cross-section. Also revolve.

Oh-gee n: An 'S'-shaped switchback curve in a line or reflection, often caused by a blistered surface.

A Surface with Oh-Gee

Pooched [surface] a: An area of surface that has an increase of convex curvature from the surface around it. (kind of like a beer-belly) Also bulged.

Radius n: A line segment extending from the center of a circle to its circumference. b: A curve defined by a given radius. c: A transitional surface between two or more adjacent surfaces which is characterized by a constant circular cross-section. v: To round out an edge between two surfaces by using transitional surface with a radial cross-section.

Sheer a: Having very little crown, or convex curvature. Almost flat.

Taut a: Having the appearance of tension.