Why is the ninth month called September?
1580s, from Middle French poinard (early 16c.), from Old French poignal "dagger," literally "anything grasped with the fist," from poing "fist," from Latin pungus "fist," from PIE root *peuk- (see pugnacious). Probably altered in French by association with poindre "to stab." Cf. Latin pugnus "fist," pugio "dagger." As a verb from c.1600.