dungeon monitor
What does dungeon monitor mean?
A dungeon monitor (DM) is the designated safety watcher at a BDSM event. While on duty their authority is effectively absolute: they patrol the space, make sure everything stays consensual and safe, and step in if something breaches house rules or looks non-consensual. Good DMs are experienced players with safety and first-aid training, and they typically don't play themselves while monitoring — the point is to stay an objective set of eyes. At private parties the host often takes the role; clubs assign trained volunteers or staff.
Origin
BDSM community role formalised through club and play-party culture; 'monitor' in the sense of a supervising steward, 'dungeon' for the play space.