n[C]a girl or woman that you are having a romantic relationship with
→
boyfriend He's never had a girlfriend .sb's girlfriend He lives in Chicago with his girlfriend.split up/break up with your girlfriend(=stop having a romantic relationship)
one of my ex-girlfriends (=former girlfriends) I didn't have a steady girlfriend (=one you have a long relationship with) .especially AmE a woman or girl's female friend
She's out with one of her girlfriends.