Nouns

(n)fire, firingthe act of firing weapons or artillery at an enemy“hold your fire until you can see the whites of their eyes”, “they retreated in the face of withering enemy fire”
(n)discharge, firing, firing offthe act of discharging a gun
(n)ignition, firing, lighting, kindling, inflammationthe act of setting something on fire
(n)dismissal, dismission, discharge, firing, liberation, release, sack, sackingthe termination of someone's employment (leaving them free to depart)