The term is most commonly used to describe any male person who is in a romantic relationship with another person.
Partners in such non-marital relationships are also sometimes described as a significant other, life partner or simply partner, especially if the individuals are cohabitating. At times, since "boyfriend" and "partner" mean different things to different people, the distinctions between the terms are subjective, and which term is used in a relationship will ultimately be determined by personal preference. In 20th century United States, women were often interviewed by Gentleman callers, men who would arrive at the home of a young woman with the hopes of a potential date.
When used by a boy or man about another male in a non-sexual, non-romantic context, especially when it's a friendship between a girl and a boy, they use the term "guy friend" so it would avoid confusion with the sexual or romantic meaning.
Though nuanced, there is a significant difference between girlfriend and boyfriend, and girl friend and boy friend. In a strictly grammatical sense, a girlfriend or boyfriend is an 'individual of significance' with whom one shares a relationship. A girl friend or boy friend, however, is simply a friend identified on the basis of gender. Since the pronunciation is the same, these words may occur to be false friends.
Unlike girlfriend, boyfriend is never used to refer to non-romantic friends (and heterosexual men do not use girlfriend to refer to their female non-romantic friends).
Additionally, gender-indiscriminate terms also apply, e.g., true love and some more specific terms such as cavalier, wooer, and gender-neutral ones like date, escort, steady or suitor; furthermore, non-gender specific euphemisms such as admirer, companion,