Hit points

A measure of a creatures abilty to suffer wounds, and to a lesser extent its current state of health. Generally a creature loses hitpoints everytime it suffers an injury, but regains them both over time and with the intervention of magic, potions, and scrolls.

When entity loses all of its hitpoints it is dead. Roguelikes differ as to whether having zero of those means death or not. Angband is an example of the latter approach.