1) Lawfully correct, legal.
2) Justified, not un-called for
4) Something very, very true
3) used to describe something in the utmost of truthiness or maybe something SO FRIKKIN DAMN AWESOME , see sick,sweet, telk, or godly
also see legit
It was a legitimate insult.
Twilight sucks, and you know it.
boy1-"check out what i scored tonight!"
boy2-"That Is Legitimate."