Noun
(US) Any select-fire firearm that allows semi-automatic and fully automatic operation, and is used or was once used by a military organization.
(US) A semi-automatic firearm that resembles a military weapon.
(New York State) A semi-automatic weapon that has a folding stock, a muzzle flash suppressor, a bayonet mount, or a pistol grip.
I consider any gun that can chamber a round and send a projectile down its barrel at a high rate of speed into my body - causing me injury or death - to be an assault weapon. Henry Rollins
There is no reason for anybody to have an assault weapon. Joe Lhota