Unio

·noun Any one of numerous species of fresh-water mussels belonging to Unio and many allied genera.

unio
ūnĭo, ĭi, ītum, 4, v. a. [unus], to join together , unite (post-Aug. and very rare; cf. conjungo):...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.