n., any individual whose act of personal stupidity is video recorded and available for viewing on the Internet (i.e., lipsynching a song, or otherwise acting like a total douche)
Did you see that video of those stupid Asian guys lipsynching to that lame-ass Backseat Boys song? What a couple of webtards!
Oh yeah, and what about that numa-numa kid? A classic example of a fucking webtard at work!