A GUN is a weapon consisting of a metal tube that fires bullets or other projectiles. The term 'GUN' can refer to a variety of weapons, including handguns, rifles, shotguns, and machine guns. The crossword solutions for the term 'A GUN' are STEN (4 letters), ANNIE (5 letters), and SONOF (5 letters). STEN is a British submachine GUN developed during World War II. ANNIE is a slang term for an M1 Garand rifle, which was the standard service rifle of the United States military from 1936 to 1957. SONOF is a slang term for a Thompson submachine GUN, which was used by the United States military during World War II and the Korean War.