Meaning of opisthobranch

o•pis•tho•branch

Pronunciation: (u-pis'thu-brangk"), [key]
— n.
  1. any gastropod mollusk of the order Opisthobranchia, as the sea slugs, sea butterflies, and sea hares, characterized by a vestigial or absent mantle and shell and two pairs of tentacles.
—adj.
  1. of or pertaining to the opisthobranches.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.