Vigorous

google

ref

Middle English: via Old French from medieval Latin vigorosus, from Latin vigor (see vigour).

wiktionary

ref

From Anglo-Norman vigrus, from Old French vigoros (French vigoureux), from Medieval Latin vigorosus, from Latin vigor. Doublet of vigoroso.

etymonline

ref

vigorous (adj.)

c. 1300 (early 13c. as a surname), from Anglo-French vigrus, Old French vigoros "strong, robust, powerful" (12c., Modern French vigoreux), from Medieval Latin vigorosus, from Latin vigere "be lively, flourish, thrive" (see vigor). Related: Vigorously.