c.1362, "trifling," from O.Fr.
petit "small" (11c.), probably from stem of L.L.
pitinnus "small," of uncertain origin, perhaps ultimately from Celtic root
*pett- "part, piece, bit" (see
piece). Attested as a surname from 1086. Replaced by
petty (q.v.) in most usages, except in established forms such as
petit bourgeois "conventional middle-class" (1853, used by Charlotte Brontë earlier than by Marx or Engels;
petty bourgeois, however, is attested from 1850),
petit mal (1842, "little evil," mild form of epilepsy), and
petit four (1884), which in Fr. means "little oven," from O.Fr.
four "oven," from L.
furnus.
[pet-ee; Fr. puh-tee] 
i