tro·choid / ˈtrōˌkoid/ • adj. 1. Anat. denoting a joint in which one element rotates on its own axis (e.g., the atlas vertebra).2. Geom. denoting a curve traced by a point on a radius of a circle rotating along a straight line or another circle (a cycloid, epicycloid, or hypocycloid).3. Zool. having or denoting a form of mollusk shell that is conical with a flat base, like a top shell.• n. 1. a trochoid curve.2. a trochoid joint.DERIVATIVES: tro·choi·dal / trōˈkoidl/ adj.

trochoid See SOLITARY CORALS.