G.I. is a noun used to describe members of the United States armed forces or items of their equipment.[1] The term is now used as an initialism of "Government Issue" (or often incorrectly "General Infantry"),[2] but originally referred to galvanized iron.
The letters "G.I." were used to denote equipment made from galvanized iron, such as metal trash cans, in U.S. Army inventories and supply records.[3][2] During World War I, U.S. soldiers sardonically referred to incoming German artillery shells as "G.I. cans." In that same war, "G.I." started being interpreted as "Government Issue" and said as an adjective of anything having to do with the Army.[2]
In comparison, the term intti in the Finnish Army has a similar history: items were marked S.A. Int. (Suomen armeijan intendentuuriosasto, Finnish Army Quartermaster General's Department), thus the word intti eventually gained the meaning "military service", "army".