[opis.tho.branch] n, pl -branchs [NL Opisthobranchia, fr. Gk opisthen behind (akin to Gk epi on) + branchia gills--more at epi-] (ca. 1856): any of a subclass (Opisthobranchia) of marine gastropod mollusks that have the gills when present posterior to the heart and often lack a shell -- opisthobranch adj
OPISTHOBRANCH
Meaning of OPISTHOBRANCH in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012