n. Originally, a weight equal to that of the Anglo-Norman silver penny, 22 ½ grains, or of a Tower pound; now, and since the eighteenth year of Henry VIII., when the use of the Tower pound was forbidden, a weight of 24 grains, or of a troy ounce. Abbreviated dwt.n. A proportional measure of one-twelfth, used in stating the fineness of silver. See carat.