of mollusks and shells, 1660s (noun and adjective), from uni- + valve.
Entries linking to univalve
uni-
word-forming element meaning "having one only," from Latin uni-, combining form of unus "one" (from PIE root *oi-no- "one, unique").
valve n.
late 14c., "one of the halves of a folding door," from Latin valva (plural valvae) "section of a folding or revolving door," literally "that which turns," related to volvere "to roll," from PIE root *wel- (3) "to turn, revolve." Sense extended 1610s to "membranous fold regulating flow of bodily fluids;" 1650s to "mechanical device that works like an anatomical valve;" and 1660s in zoology to "halves of a hinged shell." Related: Valved.