firing in WordNet English dictionary

1. the act of discharging a gun
   discharge  firing  firing off 
   
2. the termination of someone's employment (leaving them free to depart)
   dismissal  dismission  discharge  firing  liberation  release  sack  sacking 
   
3. the 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"
   fire  firing 
   
4. the act of setting something on fire
   ignition  firing  lighting  kindling  inflammation