Why is the ninth month called September?
early 13c., "gallows," from Old French gibet "gallows; a bent stick," diminutive of gibe "club," perhaps from Frankish *gibb "forked stick." The verb meaning "to kill by hanging" is from 1590s. Related: Gibbeted; gibbeting. "Originally synonymous with GALLOWS sb., but in later use signifying an upright post with projecting arm from which the bodies of criminals were hung in chains or irons after execution" [OED].