a girl who doesn't spend her time discussing issues and trying to win over others with logic but rather prefers to throw down and convince skeptics through fisticuffs or a good ass kicking.

Gwen Stefani's use:
A person who verbally postures (hollers back) in an argument and does not step up and fight. Gwen says she is not a holla back girl, implying that she will fight if challenged.

A foul, disease-ridden thing that wears too much make-up.

Yep, this is B-A-N-A-N-A-S. A song about high school cheerleaders(??) performed by a 35 year old woman.

"holla back girl" goes waaaaaaaay beyond simply not being a doormat. As noted elsewhere, at it's simplest, a "holla back girl" is one who waits for the lead cheerleader to holler, before she hollers back. In Stefani's song, she's responding to someone who said some shit about her, and she's saying teling that person that she's not the type to simply holler some shit back. Instead, she's gonna deliver an asskickin' to the shit-talker. Thus, in the context that Stefani uses the term, a "holla back girl" is someone who's nothin' but talk.

These definitions are crazy. Bunch of old white men writing em I guess. Everyone knows a Hollaback Girl is a Booty Call. A girl who you can call at any time of night and she'll show up, just for sex. see "Booty Call"

quick-pornunciation version of Hollow-back Girl, meaning a female of easy virtue; one who spends a lot of time on her back