A girl of college age that, while she herself does not belong to the Greek system (i.e., a sorority), spends a large percentage of her time with local fraternity boys. The girl usually only hangs out with one specific fraternity and over time becomes quite knowlegeable about the house and will defend the boys who live there as well as the lifestyle they may or may not live.
This behavior is usually, but not always, because the girl dates her way through the fraternity. She will usually start with a boy she meets outside the house, then circle through his friends one by one. The relationships are almost always never serious, and the girl over time becomes the charge of the boys - they will tend to look out for and defend her.
Not to be confused with a similar type of girl who actually has been inducted into the Greek system. See sorostitute
"Man, Autumn has been spending so much time at the Sigma house! And she gets really irritated when we joke about 'stupid frat boys' now."
"Yeah, but those boys will defend her right back, ya'know."
"Oh, I know. Still, she's turned into quite the fraterniwhore."