opis·​tho·​branch | \ ə-ˈpis-thə-ˌbraŋk How to pronounce opisthobranch (audio) \
plural opisthobranchs

Definition of opisthobranch

: any of a subclass (Opisthobranchia) of marine gastropod mollusks that have the gills when present posterior to the heart and often lack a shell

Other Words from opisthobranch

opisthobranch adjective

First Known Use of opisthobranch

1851, in the meaning defined above

History and Etymology for opisthobranch

borrowed from French opistobranches, plural, from Greek opistho-, combining form from ópisthen "behind, in back" + French -branches, borrowed from New Latin -brancha or -branchia "having gills (of the kind specified)," based on Latin branchia "gills," borrowed from Greek bránchia; ópisthen variant (with -s- after prósthen "before, in front" and opísō "backward") of ópithen, from opi- (going back to Mycenaean Greek o-pi "on, for," going back to Indo-European *h1opi, o-grade form of *h1epi "on") + -the(n), going back to Indo-European *dhe, locative particle — more at branchial, epi-

Note: The vernacular taxonomic name opistobranches (later Latinized as Opisthobranchia, with the erroneous spelling -st- corrected to -sth-) was introduced by the French zoologist Henri Milne-Edwards (1800-85). It appears first in a report to the Société Philomathique de Paris, Extraits des procès-verbaux des séances pendant l'année 1846, Séance du 1er août 1846, p. 116, and in a more detailed presentation in "Notes sur la classification naturelle des mollusques gastéropodes," Annales des sciences naturelles, 3. série (Zoologie), tome 9. (1848), pp. 102-12.

Learn More About opisthobranch

Time Traveler for opisthobranch

Time Traveler

The first known use of opisthobranch was in 1851

See more words from the same year

Dictionary Entries Near opisthobranch




See More Nearby Entries 

Statistics for opisthobranch

Cite this Entry

“Opisthobranch.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/opisthobranch. Accessed 5 Dec. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More from Merriam-Webster on opisthobranch

Britannica.com: Encyclopedia article about opisthobranch


Test Your Vocabulary

Farm Idioms Quiz

  • cow coming home
  • What does 'poke' refer to in the expression 'pig in a poke'?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!