Term used to rate an attractive woman inconspicously through a system ranging from 1 to 5 (with halves still applicable). 5 is the highest rating given to near perfection, wheras 1 is so inconsequential that it is not worth mentioning. The rate of 2.5 is given to a female that is attractive enough to hook up with while drunk, a 3 is a fairly attractive woman that is pleasant.
Basic rules of the factor system are:
1. You don't tell the female what her factor number is
2. You don't rate your friends girlfriend or wife to his face
3. You don't take personality into account, it's solely based on looks
1. Oliva Munn is a factor 5.
2. It's getting late and the bars about to close, I'll take that factor 2.5 home