Definition of friendly fire
: the firing of weapons from one's own forces or those of an ally especially when resulting in the accidental death or injury of one's own personnel
- Near the river bordering our camp I find the tents of the four soldiers who were supposedly hit by friendly fire.
- —Janine Di Giovanni
- After all, accidental attacks, though tragic, are common in war. In 1967 alone, "friendly fire" killed 5,373 Americans fighting in Vietnam.
- —Michael Oren
