Use of the word Metagame in poker context

[sudic]

I got tired of reading the word Metagame in some of the poker posts and not understanding its use. so I finally looked it up.

From Wikipedia,
Metagaming is a broad term usually used to define any strategy, action or method used in a game which transcends a prescribed rule set, uses external factors to affect the game, or goes beyond the supposed limits or environment set by the game.

In role-playing games, metagaming is the use of out-of-character knowledge in an in-character situation. A character played by a metagamer does not act in a way that reflects the character's in-game experiences and back-story.

Would someone explain the use of the word Metagame in poker context?

thanks!