An internet chat language variety/version of the word "owned", used in the sence of beating/defeating/outclassing someone. Usually used in games such as Counter-strike or on messageboards when a user posts arguments or insults that can't possibly be counter-argued.
Arguably considered so-called "l33t-speak"
a word used in place of "owned"
the word was used originally only by accident, when someone's finger slip while typing the word "owned" (as you may notice on your keyboard, the "p" is just to the right of the "o")
somewhere along the line, some people deicided to use it as a joke and the joke spread more and more.
then, some decided to take out the e, so instead of "pwned" we have "pwnd", but some still use it in it's original form with the "e". some also spell it "pwn'd" with an apostrophe in place of the "e".
frank: yeah, he totally got pwnd.
ben: man, that asian cobra didn't stand a chance against that mongoose.
frank: yeah, that cobra got pwnd.
The term refers to figuartively getting your ass beat in by a forty-something year-old prison inmate, i.e. getting your shit kicked; getting your ass whooped; getting knocked out; you lose bitch.