opisthobranch

noun opis·tho·branch \ə-ˈpis-thə-ˌbraŋk\

plural opis·tho·branchs

Definition of OPISTHOBRANCH

: 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 adjective

New Latin Opisthobranchia, from Greek opisthen behind (akin to Greek epi on) + branchia gills — more at epi-

First Known Use: circa 1856

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