n (uncountable) A (usually self-sustaining) chemical reaction involving the bonding of oxygen with carbon or other fuel, with the production of heat and the presence of flame or smolder|smouldering.
n (countable) Something that has produced or is capable of producing this chemical reaction, such as a campfire.
n (countable) The often accidental occurrence of fire in a certain place leading to its full or partial destruction.
n (context|China, India and Japan) One of the five basic elements (see (w|Classical_element|Wikipedia article on the Classical elements)).
n (countable) A button (of a joypad, joystick or similar device) whose only or main current function is that when it is pressed causes a video game character to fire a weapon.
v (transitive) To terminate the employment contract of (an employee), especially for cause (such as misconduct or poor performance).
v (intransitive|computer sciences, software engineering) To initiate an event (by means of an event handler)