opis·​tho·​branch ə-ˈpis-thə-ˌbraŋk How to pronounce opisthobranch (audio)
plural opisthobranchs
: any of a subclass (Opisthobranchia) of marine gastropod mollusks that have the gills when present posterior to the heart and often lack a shell
opisthobranch adjective

Word History


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.

First Known Use

1851, in the meaning defined above

Time Traveler
The first known use of opisthobranch was in 1851

Dictionary Entries Near opisthobranch

Cite this Entry

“Opisthobranch.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/opisthobranch. Accessed 5 Jun. 2023.

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