Definition of unionoid in English:

unionoid

adjective

Zoology
  • Of or relating to the family Unionidae of freshwater mussels, or the order Unionoida in which they are included; unioniform.

noun

Zoology
  • A mollusc of the family Unionidae or order Unionoida; a freshwater mussel.

Origin

Late 19th century; earliest use found in Henry Nicholson (1844–1899), biologist and geologist. From scientific Latin Unio unio + -oid, with insertion of -n- after classical Latin ūniōn-, ūniō, etymon of the first element.

Pronunciation

unionoid

/ˈjuːnɪənɔɪd/