an arrondissement in the department of the Orne, in France, extending over 729 square miles, or 466,690 acres. It comprehends 11 cantons, divided into 190 communes. Population in 1851, 106,854. The chief city of the arrondissement is of the same name. It is situated on an elevation in a beautiful plain, through which the Orne runs. It contains 5425 inhabitants, who manufacture thread-lace of a fine quality, some linen goods, and leather.