A person that lives a life of promiscuity is someone that's considered 'promiscuous' - meaning they are very sexually loose and not at all bothered about remaining loyal to one sexual partner.
E.g A man that can't go to a bar without ending up sunk to the nuts inside someone else by the end of the night, or a woman that can't keep her legs closed and hands sex out on a platter to others. A slut, basically.
Also the name of a 2006 mainstream song by Nelly Furtado featuring Timbaland.
One who perpetuates acts of promiscuity outwardly; a slut, only in a more proper sense.
Guy: "Damn. I always thought Jenny was so sophistocated, but today she just walked right up to this guy and made out with him WITH HER BOYFRIEND WATCHING."
Other Guy: "Yeah, she always was quite the promiscuitor."