A male who is friends with a female. This is used in contrast boyfriend. A guyfriend is just a friend who happens to be a guy; a boyfriend is someone you are dating.
a dude, a fun guy to hang out with and talk to when all ur girlfriends are bein goofballs. u usually end up dating ur guyfriend for a while but it hardly ever works out cuz hes basically ur brother
girl: ur my best guyfriend
boy: i know, but i kinda want to be your boyfriend girl: o well i guess we could try that