gun vs firing mechanism

gun and firing mechanism both are nouns.

Word	Noun	Adjective	Verb	Adverb
gun	Yes	No	Yes	No
firing mechanism	Yes	No	No	No

gun (noun)	firing mechanism (noun)
the discharge of a firearm as signal or as a salute in military ceremonies	the action that ignites the charge in a firearm
a weapon that discharges a missile at high velocity (especially from a metal tube or barrel)
large but transportable armament
a hand-operated pump that resembles a pistol; forces grease into parts of a machine
a pedal that controls the throttle valve
a professional killer who uses a gun
a person who shoots a gun (as regards their ability)

gun (verb)	firing mechanism (verb)
shoot with a gun