The act of dominating an adversary in a written or verbal debate. Similar to pwn, a werdpwn occurs when the opponent's argument is completely, utterly rebuked, or at the very least you unleash a real good burn which makes the opposing argument (or the opponent itself) look foolish or silly.
Opponent: i invented internets when i was eleven and made a million dollars
You: you were born in 1993 and the internet was invented liek 15 years before that, and you suck at halo. noob.
Onlooker: nice werdpwn
Onlooker: u just got werdpwned. lol