Definition of trochoid:
(n) :
(geometry) The curve traced by a point on a circle as it rolls along a straight line
(n) :
(malacology) An organism or fossil with a trochoid shell (especially one in the gastropod family Trochidae), or the shell itself.
(adj) :
Capable of rolling.
(adj) :
Allowing rotation.
(adj) :
(malacology, of a shell or fossil) High-spired; conical.