Definition: Pwned is a slang version of the word "owned," which is often used by gamers to describe a particularly humiliating defeat. Pwned was such a common typo seen in the chat windows of early online shooters that it eventually became part of gamer vocabulary. No doubt, the proximity of the 'O' and 'P' keys on a standard keyboard is partially to blame for this. In a similar way, you will frequently see "the" deliberately misspelled "teh."
Examples:We really pwned that clan. They must be noobs.