Definition:
Argumentative- contentious and disagreeing.


Example:
“And just because some other webmaster says that his Xbox is working fine, well, that's even less scientific than the other assessment. The fact of the matter is that you and I don't know *bleep* about *bleep* where this is concerned, and what's more, it likely doesn't matter.”
“News Post on the Penny Arcade,” By Tycho Brahe


Explanation:
The speaker is clearly disagreeing with whomever it is he’s talking about. He does not believe that the opinion of the other person is valid, and is in the dying throes of an argument.