adj of or pertaining to the genus trochus or family trochidae.
2. trochoid ·adj top-shaped; having a flat base and conical spire;
said of certain shells.
3. trochoid ·adj admitting of rotation on an axis;
sometimes applied to a pivot joint like that between the atlas and axis in the vertebral column.
4. trochoid ·noun the curve described by any point in a wheel rolling on a line; a cycloid; a roulette; in general, the curve described by any point fixedly connected with a moving curve while the moving curve rolls without slipping on a second fixed curve, the curves all being in one plane. cycloids, epicycloids, hypocycloids, cardioids, ·etc., are all trochoids.