What's your definition?

I see it used most everywhere, the terms slut and whore, but what are your personal definitions? 
I'm not trying to start fights? I genuinely want to know what people consider a slut. 
My own say in the matter is that whores sell themselves so calling a girl a whore because she had sex is nullified since she didn't sell herself but what about slut? What constitutes the use of the word?
I don't think a girl should be called slutty because she's had lots of sex or likes to party with the guys(or girls depending on which way she swings)
But what about you girls? Opinions?
Please no harassing one another