an arrondissement in the department of Vaucluse in France, extending over 453 square miles, or 290,288 acres. It is divided into five cantons, and 50 communes. Pop. in 1851, 55,916.

(Apta Julia), capital of the arrondissement of that name, situated in a rich valley on the left bank of the river Calavon, and surrounded by old walls. It is the seat of a bishop, and has a court of primary jurisdiction, a society of agriculture, and a college. Population in 1851, 5699, engaged in the manufacture of woollen and cotton stuffs, confections, brandy, earthenware; also in silk-spinning, blanching wax, &c.; besides which they export grain, wines, truffles, almonds, fruits, and cattle. Apt, one of the most ancient cities of Gaul, was restored by Julius Cesar, who built across the river a fine bridge of one arch, which still exists. The Gothic cathedral is of high antiquity, and the town presents various objects of antiquarian interest. Long. 5° 23' 47" E. Lat. 43° 52' 29" N.