Meaning of GAMMA in English

I. ˈga-mə noun

Etymology: Middle English, from Late Latin, from Greek, of Semitic origin; akin to Hebrew gīmel gimel

Date: 15th century

1. : the 3d letter of the Greek alphabet — see alphabet table

2. : the degree of contrast of a developed photographic image or of a video image

3. : a unit of magnetic flux density equal to one nanotesla

4. : gamma ray

gamma counter

5. : microgram

II. adjective

Date: 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 — symbol γ

Merriam-Webster's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.