A girlfriend is a female friend, possibly specifying a female partner with whom one is romantically and/or sexually involved.
Partners in committed non-marital relationships are also sometimes described as a “significant other” or simply “partner”, especially if the individuals are cohabiting.
“Girlfriend” and “partner” mean different things to different people; the distinctions between the terms are subjective. How the term is used will ultimately be determined by personal preference.
In 2005, a study was conducted of 115 people ages 21 to 35 who were either living with or had lived with a romantic partner. It notes that the lack of proper terms often leads to awkward situations, such as someone becoming upset over not being introduced in social situations to avoid the question.
There exists some ambiguity between the terms “girl friend,” or a friend who is a girl, and “girlfriend.” The transition between the two is a significant aspect of adolescent development.