The degree at which a person (usually female) is slutty. Those who have an excess amount of sluttitude are more prone to engage in slut-oriented acts. Such as cheating on significant others, dating best friends, and getting the most drunk at that last party and grinding on everyone... you know the one.
"Man, last weekend Sarah reached a whole new level of sluttitude when she macked on that dude with no legs.. I mean, everybody needs loving.. but Christ"
"Those bisexuals have a sluttitude factor beyond comprehension"