A sent of Axe deodorant, it smells like frozen lemon and eucalyptus. A good sent, unto which a great many noble men seem to enjoy to thy fullest.
P1: Hey bro, I played Minecraft for 30 hours recently.
P2: good thing you have axe-ice chill deodorant to keep you fresher than a blue loli.
P1: indeed my fellow manly degenerate!
It's a word put together from Chillin' and Relaxing. It actually means the same. If somebody should cool down you could say he or she has to relax or has to chill out. If you decide not to choose between these to, or you haven't made a decision while you already have to say the word, you say 'Chillax'.