"plant-eating animal," 1851, from Modern Latin Herbivora (1830) or French herbivore (1748), from neuter plural of Latin herbivorus, from herba "a plant" (see herb) + vorare "devour, swallow" (from PIE root *gwora- "food, devouring").
c. 1300, erbe "non-woody plant," especially a leafy vegetable used for human food, from Old French erbe "grass, herb, plant fed to animals" (12c., Modern French herbe), from Latin herba "grass, an herb; herbage, turf, weeds" (source also of Spanish yerba, Portuguese herva, Italian erba). The form of the English word was refashioned after Latin since 15c., but the h- was mute until 19c. Slang meaning "marijuana" is attested from 1960s. The native word is wort.