Bayonet

Bayonet is a swordlike stabbing blade, a kind of short dagger, used by soldiers in hand-to-hand fight. It can be fixed to the muzzle of a rifle. It derives its name from the French town Bayonne where it was first made.

Bayonet is also a fitting with a socket into which light bulb, camera lens, or any other appliance can be pushed and twisted to lock it.