n. An old weight equal to a scruple, or the twenty-fourth part of an ounce troy.n. A unit of mass formerly used in various countries for weighing gold.n. Hence A twenty-fourth part: specifically used in expressing the fineness of gold when used as jewelry.n. A unit of weight for precious stones, divided by jewelers into 4 grains, called diamond-grains, but equal to about 3⅙ troy grains, 151½ English carats being taken as equal to an ounce troy.n. Often abbreviated car. or K.To try or refine (gold).n. An Arabian coin of base silver, current in Mecca, Medina, and Mocha.