The Collaborative International Dictionary
Trochal
Trochal \Tro"chal\, a. [From Gr. ? a wheel.] (Zo["o]l.) Resembling a wheel.
Trochal disk (Zo["o]l.), the cephalic disk of a rotifer. It is usually surrounded by a fringe of cilia.
Wiktionary
trochal
a. (context zoology English) Resembling a wheel.