permadeath

noun2

1. •
   Permanent death, where the player cannot continue but is obliged to restart the game from the beginning.

   • And yes, especially 'special' mobs coming back is a bit of a stretch. But then the players coming back is a stretch too, no? (yes, I know, many have implemented some form of permadeath). — 1996
2. •
   Likewise, any situation where a player character or characters who die are lost permanently but do not trigger a game over, allowing the player to proceed without the character(s). Particularly applies if said deaths are avoidable (not forced by the plot) and occur only as a result of player blunder.

   • For many fans of the dungeon crawler genre, the ultimate risk is permadeath. And it’s just what it sounds like. If you die in a game with permadeath, your character is toast. Gone. Permanently. — 2015