From Bouvier's Law Dictionary, Revised 6th Ed (1856) :
COIN, commerce, contracts. A piece of gold, silver or other metal stamped by authority of the government, in order to determine its value, commonly called money. Co. Litt. 207; Rutherf. Inst. 123. For the different kinds of coins of the United States, see article Money. As to the value of foreign coins, see article Foreign Coins.