c. 1200, from Old French assalir "attack, assault, assail" (12c., Modern French assaillir), from Vulgar Latin *adsalire "to leap at," from Latin ad- "at" (see ad-) + salire "to leap" (see salient (adj.)). Figurative use from mid-14c. Related: Assailed; assailing; assailable.[assail etymology, assail origin, 英语词源]