The abbreviation G.I. is most commonly used to shorten government issue, and has different meanings depending on the part of speech in which it is used.
As a noun, G.I. refers to a soldier in the US Army or, less commonly, any person in the US military.
As an adjective, it modifies any item given to a soldier by the Army, or any procedure used by the army, to distinguish it from civilian versions.
When used as a verb, G.I. is a synonym for square away, as in "Top, get the unit to G.I. this AO before the old man arrives."
Historical origin
G.I. was originally an abbreviation for Galvanized Iron, a US Army clerks' term for items such as G.I. cans: trash cans that are galvanized. G.I. cans was also used to refer sardonically to shells fired by the German Army in WWI.
Between WWI and WWII usage of the abbreviation expanded to stand for Government Issue and applied to all articles issued in conformity with US military regulations or procedures. By WWII it had become a nickname for the soldiers themselves.
See also
