Why is the ninth month called September?
1520s, from an obsolete adjective meaning "reduced to nothing" (late 14c.), originally the past participle of a verb, anihil, from Old French annichiler (14c.), from Late Latin annihilare "to reduce to nothing," from Latin ad- "to" (see ad-) + nihil "nothing" (see nil). Related: Annihilated; annihilating.