So good looking that the words "beautiful" or "handsome" just don't give justice to how incredible attractive something may be.
An amazing feeling that words alone can't describe the passion you have for something, and the closest word to describing that passion without making it sound dull.
Person 1: Do you see that blonde, almost naked chick over there?
Person 2: Yea! She is so sexy!
Person 1: I heard you and your boyfriend made out yesterday in the hot tub.
Person 2: We did! It was steamy and sexy!