n (Weapon) A pointed instrument of the dagger kind fitted on the muzzle of a musket or rifle, so as to give the soldier increased means of offence and defence. Originally, the bayonet was made with a handle, which required to be fitted into the bore of the musket after the soldier had fired.
n (Machinery) A pin which plays in and out of holes made to receive it, and which thus serves to engage or disengage parts of the machinery.