noun

• (US, law enforcement) Initialism of Alcohol, Tobacco and Firearms. (the Bureau of Alcohol, Tobacco, Firearms and Explosives)
• (automotive) Abbreviation of automatic transmission fluid.
• (aviation) Abbreviation of aviation turbine fuel.; jet fuel
• (US, military, aviation) Initialism of advanced tactical fighter.
• (US, military, nautical) Initialism of auxiliary tugboat fleet.; a naval fleet tugboat, a fleet tug that can keep up with a fleet on operations