[GI] adj [galvanized iron; fr. abbr. used in listing such articles as garbage cans, but taken as abbr. for government issue] (ca. 1935) 1: provided by an official U.S. military supply department "~ shoes"
2: of, relating to, or characteristic of U.S. military personnel
3: conforming to military regulations or customs "a ~ haircut"
[2]GI n, pl GIs or GI's (1943): a member or former member of the U.S. armed forces; esp: a man enlisted in the army [3]GI adv (1949): in a strictly regulation manner [4]GI vt GI'd ; GI'.ing (1951): to clean thoroughly (as floors) in preparation for or as if for a military inspection