opisthobranch

American  

[uh-pis-thuh-brangk] / əˈpɪs θəˌbræŋk /

Also opisthobranchiate

noun

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.

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adjective

1. of or relating to the opisthobranches.

opisthobranch British  

/ əˈpɪsθəˌbræŋk /

noun

1. any marine gastropod of the class Opisthobranchia (or Opisthobranchiata ), in which the shell is reduced or absent: includes the pteropods, sea hares, and nudibranchs

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Etymology

Origin of opisthobranch

1850–55; < New Latin Opisthobranchia the subclass; opistho-, branchia