early 15c., "capable of life or growth; growing, vigorous;" also "neither animal nor mineral, of the plant kingdom, living and growing as a plant," from Old French vegetable "living, fit to live," and directly from Medieval Latin vegetabilis "growing, flourishing," from Late Latin vegetabilis "animating, enlivening," from Latin vegetare "to enliven," from vegetus "vigorous, enlivened, active, sprightly," from vegere "to be alive, active, to quicken," from PIE root *weg- "to be strong, be lively." The meaning "resembling that of a vegetable, dull, uneventful; having life such as a plant has" is attested from 1854 (see vegetable (n.)).
mid-15c., "non-animal life," originally any plant, from vegetable (adj.); specific sense of "plant cultivated for food, edible herb or root" is first recorded 1767. Meaning "person who leads a monotonous life" is recorded from 1921; sense of "one totally incapacitated mentally and physically" is from 1976.
The Old English word was wyrt (see wort). The commonest source of words for vegetables in Indo-European languages are derivatives of words for "green" or "growing" (compare Italian, Spanish verdura, Irish glasraidh, Danish grøntsager). For a different association, compare Greek lakhana, related to lakhaino "to dig."