Tristoma

‖Tris″to‐ma (?), n. [NL., from Gr. � (see Tri-) + � mouth.] (Zoöl.) Any one of numerous species of trematode worms belonging to Tristoma and allied genera having a large posterior sucker and two small anterior ones. They usually have broad, thin, and disklike bodies, and are parasite on the gills and skin of fishes.