"Pewn" is dreived from the word "Pwn" which is derived from the word "own" and has escentally the same meaning as the words from which it came.
Other variations of the word pewn may be seen on rare occasion. Such as "pewnage" (a variation of ownage) or "p3wnz0r" or any other variation of the word written in 1337 text. Theese variant versons of the word "pewn" are quite rare however and are generally only used by lamers or by pros who are joking around.
Player 2 defends the attack dealing 10,000 damage. Player 1 was pewned.
Also can be said as pewned and pewnage.
Not really a meaning to it, just a word you can use in many different situations.
Let's go right now I'm gonna pewn you!