trochoid

English

Etymology

From Ancient Greek τροχοειδής (trokhoeidḗs), from τροχός (trokhós, “wheel”) + εἶδος (eîdos, “form, image”).

Noun

trochoid (plural trochoids)

1. (geometry) The curve traced by a point on a circle as it rolls along a straight line
2. (malacology) An organism or fossil with a trochoid shell (especially one in the gastropod family Trochidae), or the shell itself.

Adjective

trochoid (comparative more trochoid, superlative most trochoid)

1. Capable of rolling.
2. Allowing rotation.
3. (malacology, of a shell or fossil) High-spired; conical.

   

   Bartsch's star bolma has a trochoid shell.