n. [ Rhino- + Gr. fe`rein to bear. ] (Zool.) One of the two tentacle-like organs on the back of the head or neck of a nudibranch or tectibranch mollusk. They are usually retractile, and often transversely furrowed or plicate, and are regarded as olfactory organs. Called also dorsal tentacles. See Illust. under Pygobranchia, and Opisthobranchia. [ 1913 Webster ]