metagaming

the act of using outside or previously gained knowledge within a gaming universe for personal gain or advantage.
john was accused of metagaming when he immediately moved his player to the most protected area of the map to snipe the enemy team members, since he had played the map before and knew from experience.
6 more definitions
when game information outside of what is available in a game is used to give a player an advantage in-game. most commonly seen and frowned upon in many forms of role playing especially when consent has not been given.
example a.

a dungeons and dragons adventure team comes across an unknown monster in-game. the metagamer knows this monster through out-of-game information. using this information, the metagamer’s character acts upon the monster’s weaknesses and attributes despite the character having never seen the monster before.

example b.

in an online pan-fandom rpg, ryoga from ranma 1/2 meets ken from street fighter for the first time and they have a fight to the death. ken finds some water in a random nearby bucket and dumps it on ryoga, then proceeds to pummel the life out of ryoga who is now transformed into a tiny black pig because of his water curse.

in this case, ken’s role player is metagaming.
a common term used in role-playing game that tells real life details or something that goes beyond the limits or environment set by the game.
often frowned apon in role-playing.
some metagaming noob wanted his job as the mayor back after he stated that he supposedly “lagged out of the server.”

that metagamer was banned from the server for calling the police to report a marijuana plant sticking through a wall outside a player owned apartment.
metagaming is when someone playing a game is using perception involving content not included with the game, and using it to their advantage. it is also commonly used, and perhaps not correctly, for when someone has died in a game, remembers their last location, and uses that information to go back there and kill them vengefully.
player #1 kills player #2
player #2: f-ck you i know where you are now!
player #1: don’t be a d-ck, that’s metagaming.
the act of discovering a way to express something in a way to avoid socially awkward behavior. which in itself is also a socially awkward behavior. that’s like inception deep.
we’re totally meta-gaming a way to make out with babes while filming our movies.
predicting an opponent’s decision in compet-tive gaming as a result of -n-lysis of the opponent’s past decisions.
there is a special set of moves in chess which allows a player to win in four moves. compet-tor a has been watching compet-tor b play chess, and the past five games in a row compet-tor b has attempted to use this four-move win. when compet-tor a sits down to play against compet-tor b, compet-tor a will be metagaming if he/she plays in a way that will easily thwart the four-move checkmate before compet-tor b makes it obvious that this is what he/she is doing.

-from wikipedia
using in-game exploits to gain an advantage over other players.
using the “noob tube” in cod: modern warfare 2. ie: metagaming.