... NOT "defiantly." (And not "definately," either... just to keep me humble, dammit.)
Yeah, so it's one of my pet peeves (kind of like how some people hate "ridiculous" being spelled wrong--which I also dislike, but not hate as passionately as "defiantly"), and I've been noticing it all over the place on the boards.
I'm not a spelling nazi, but when an otherwise simple word gets commonly accepted as being spelled correctly, when in fact it is NOT correct, it gets under my skin. (E.g. my students used to uniformly spell "outcast" as "outkast," thanks to pop music being more important than their spelling tests.)
I mean, sure, if you're "definitely" feeling X way about X topic, then maybe you're also "defiantly" feeling that way... but come on, it just sounds silly. The two words have such utterly different meanings... how can you blindly trust the spell-checker...