Why is the ninth month called September?
mid-14c., "trifling," from Old French petit "small, little, young, few in numbers" (11c.), probably from stem of Late Latin pitinnus "small," of uncertain origin; it corresponds to no known Latin form and perhaps is from a Celtic root pett- "part, piece, bit" also found in Italian pezza, English piece. Attested as a surname from 1086. Replaced by petty in most usages, except in established forms such as petit bourgeois "conventional middle-class" (1832; used in English by Charlotte Brontë earlier than by Marx or Engels); petit mal (1842, literally "little evil," mild form of epilepsy), and petit four (1884), which in French means "little oven," from Old French four "oven," from Latin furnus.