A boyfriend is a male partner in a non-marital romantic relationship with either a woman or a man.
In contrast to its female equivalent, girlfriend, which is often used to describe a woman's close female friends, the term is rarely used in reference to non-romantic relationships. It is a relatively modern term, and in the past has had implications of an illicit relationship (as sexual and romantic relationships outside marriage were generally frowned upon). It is now a generally accepted term, however, no longer having negative connotations. The term is more likely to be used to describe a boy or a young man in a relationship, as an older man in a non-marital relationship is often described as a significant other or partner. Even amongst younger people, boyfriend may be replaced with the gender-neutral term partner, especially when describing a young man in a long term relationship.
See also