jack·a·napes \ˈjakəˌnāps\noun (-es) Etymology: Middle English Jack Napis, Jac Napes, nickname for William de la Pole died 1450 4th earl and 1st duke of Suffolk 1.: monkey, ape 2. a.: an impertinent or conceited fellow : coxcomb < beribboned jackanapes — Frank Yerby > b.: a pert or mischievous child