Arena
Also said as Combat space, Kill box, Lock-in
A space built for one fight: big enough to move around in, usually with exits closed until it ends. The room itself sets the terms, so you can't solve it by backing into the last corridor.
Enemies can't pressure a player who has found a safe doorway. Close the doors and players have to use the whole room, which is where the fight you actually designed takes place.
Say it
“Players are camping the entrance and shooting demons as they come through. Seal that door when the first wave spawns, and put health at the far side of the room.”
Where you’ve seen it
Doom (2016) locks you into arenas until every demon is dead, and health and ammunition come from killing them, so standing still is the worst thing you can do.
Not to be confused with corridor fight
In a corridor, enemies come from one direction, one at a time. In an arena they come from all sides, and your position changes all the time.