herbivore n.

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.

also *gwera-, Proto-Indo-European root meaning "food, devouring."

It forms all or part of: carnivorous; devour; gorge; gurges; hellebore; herbivore; herbivorous; insectivore; locavore; omnivorous; voracious; voracity; -vorous.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit girati "devours, swallows," garah "drink;" Avestan aspo-gar- "devouring horses," nere-gar- "devouring men;" Greek bobroskein "to eat, digest," brotos "edible," brosis "eating," bora "fodder;" Latin vorare "to swallow, devour;" Armenian e-ker "ate;" Lithuanian gerti "to drink," gìrtas "drunk;" Old Church Slavonic žiro "to swallow," grŭlo "gullet," po-žreti "to eat" (of animals), "to devour."