In game: In character, as your character, not in the real world.
Off game: Out of character, as your real person in the real world.
Meta techniques: Techniques used to enhance the experience that breaks the illusion of the game. For example techniques to inform other players of your characters thoughts.
Black box: Area where you are off game and can play out scenes that are not part of the main story, such as memories, flashbacks and/or dreams.
Transparency: A method of LARP:ing where you as a player know more than your character.
Immersion/360°: To be in a world that are completely fictional where nothing should make you think of the real world outside of the game.
Safety words: Code words used to break a scene or calm a scene if you as a player feel uncomfortable with how the game is going.