Why is the ninth month called September?
late 14c., earlier asaut (c.1200), from Old French asaut, assaut "an attack, an assault, attacking forces" (12c.), from Vulgar Latin *adsaltus "attack, assault," from ad "to" (see ad-) + Latin saltus "a leap," from salire "to leap, spring" (see assail). In law by 1580s; historically, assault includes menacing words or actions; battery is an actual blow.
early 15c., from Middle French asauter, assauter, from Vulgar Latin *assaltare (see assault (n.)). Related: Assaulted; assaulting.