PROSOBRANCH

noun (plural -branchs) Etymology: New Latin Prosobranchia, from proso- in front (from Greek prosō forward) + branchia gills (from Greek) Date: 1851 any of a subclass (Prosobranchia) of gastropod mollusks that have the loop of visceral nerves twisted into a figure eight, the sexes usually separate, and usually an operculum, ~ adjective