What is a troy weight containing twenty-four grains, or the twentieth part of an ounce; as, a pennyweight of gold or of arsenic. It was anciently the weight of a silver penny, whence the name called?

pennyweight — A troy weight containing twenty-four grains, or the twentieth part of an ounce; as, a pennyweight of gold or of arsenic. It was anciently the weight of a silver penny, whence the name. (Webster's 1913.)

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