A large woman (either muscular or over weight) who has excessive strength like that of a primate. She is able to defeat the average woman in a combative situation and has been known to rival some men. Usually they are not very attractive, in excess of 200 pounds, have a very unpleasant disposition and tend to run in packs or families like the African lowland gorillas. Many pretty girls have one girlrilla friend that accompanies them to clubs, parties, etc. to ward off unwanted advances from men or other women similar to having a bodyguard.
Lance and Dennis called Karren a name at the club and embarrassed her so Karren's girlrilla friend beat the crap out of both of them.