1. Someone injured or killed or captured or missing in a military
engagement2. Fatal
accident: an
accident that causes someone to die
3. A decrease of military personnel or equipment
1.
Officer: "We need medical support, we have three casualties, two of 'em fatal."
2.
Newscaster: "There's been a casualty with the
airliner, a wiring problem caused it to crash, killing over a hundred passengers."
3. Soldier 1: "Where's our extra ammo?"
Soldier 2: "HQ didn't send any."
Soldier 1: "Another casualty, eh?"