Arzamas, Or Arsamas, a town of European Russia, capital of a district, in the government and 60 m. S. of the city of Nizhni Novgorod, on the Tyesha; pop. in 1867, 10,517. It is an old town, and has 34 stone churches, a fine cathedral built in 1812-'41, several convents, manufactures of silk, linen, iron, and leather, and two annual fairs.

AS, a Roman weight, equivalent to the libra of 12 ounces. It was also the name of a Roman brass coin, originally an as in weight, but reduced at successive times, until it weighed' but half an ounce; it was stamped at first with the figure of a sheep, ox, or sow, afterward with the face of Janus, and a ship's prow.