Definition of opisthobranch in English:

opisthobranch

Pronunciation /əˈpisTHōˌbraNGk/ /əˈpɪsθoʊˌbræŋk/

noun

Zoology
  • A marine mollusk of a group that includes the sea slugs and sea hares. They have a small or absent shell and are typically brightly colored with conspicuous external gills.

    Subclass Opisthobranchia, class Gastropoda