Why is the ninth month called September?
1520s, from Middle French jacquerie "peasants or villeins collectively," from Jacques, the proper name, which is used as Jack is used in English, in the sense of "any common fellow." So, also, "the rising of the northern French peasants against the nobles, 1357-8," from a French usage. Etymologically, Jacques is from Late Latin Iacobus (see Jacob).
insurrection of peasants against the nobility in northeastern France in 1358-so named from the nobles' habit of referring contemptuously to any peasant as Jacques, or Jacques Bonhomme