pennyweight

noun

1. (in troy weight) a unit of 24 grains or 1/20 of an ounce (1.56 grams). Abbreviation: dwt, pwt

noun

1. a unit of weight equal to 24 grains or one twentieth of an ounce (Troy)

n.Old English penega gewiht, originally the weight of a silver penny; see penny + weight (n.).