n. A variety of the mineral beryl, having a deep, clear green color, and when transparent highly prized as a gem.n. The name in Great Britain of a size of printing-type, intermediate between minion (which is larger) and nonpareil (which is smaller), and measuring 138 lines to the foot. It is not used in the United States.n. In entomology, one of several small green geometrid moths, as the grass emerald, Pseudoterpna pruinata, and the Essex emerald, Phorodesma smaragdaria.Of a bright green, like emerald.