Well, I guess you can just look at the title and see the correct way. But yeah. Why can't anyone spell this word? It's not "defintly," it's not "defiantly," it's not "defnitley." I should also point out the difference between these two words because they are mixed up all the time:

Definite / definitely: for sure, certain, without a doubt. (pronounced DEF-in-it-ly)

Defiant / defiantly: stubborn, rebellious, uncooperative. (pronounced dee-FY-ant-ly)

I don't usually quibble over this stuff but there you go.