[gam.ma] n [ME, fr. LL, fr. Gk, of Sem origin; akin to Heb gimel gimel] (15c) 1: the 3d letter of the Greek alphabet
2: the degree of contrast of a developed photographic image or of a television image
3: a unit of magnetic flux density equal to one nanotesla
4: gamma ray--usu. used as the attributive form of gamma ray "~ counter"
gamma adj (1896) 1: of, relating to, or being one of three or more closely related chemical substances
2: third in position in the structure of an organic molecule from a particular group or atom