A Grammatical Dictionary of Botanical Latin

Opus,-untis (s.f.III), abl.sg. Opunte = Gk. opous, “a town of Locris in Greece, now Kardhenitza” (Lewis & Short); Opuntian Locris = a narrow strip upon the east coast of central Greece; see opuntioideus,-a,-um (adj.A).

Opuntius,-a,-um (adj.A): Opuntian, of or pertaining to the Greek town ‘Opus.’

Opuntii,-orum (pl.m.II): the inhabitants of Opus, the Opuntians (Lewis & Short).

Opuntia,-ae (s.f.I) L. Prickly pear. “Greek name for a different plant which grew around the ancient town of Opus in Greece, the chief town of a tribe called from it the Locri Opuntii; the name ‘Opus’ is supposed to mean the town of figs. Cactaceae” (Stearn 1996); see cactus,-i (s.m.II); see tuna,-ae (s.f.I).

Opuntia (Eng.noun): “a very large genus of cacti comprising the prickly pears, … having flat or terete joints usu. studded with tubercules that bear sharp spines, prickly hairs, or both…; any cactus of the genus Opuntia” (after WIII).

-opus: nouns ending in -opus = -o- + -pus; see -pus, gen. sg. -podis (s.m.III), ‘foot.’