Gay is a term that primarily refers to a homosexual person or the trait of being homosexual. The term originally meant 'carefree', 'cheerful', or 'bright and showy'. While scant usage referring to male homosexuality dates to the late 19th century, that meaning became increasingly common by the mid-20th century. In modern English, gay has come to be used as an adjective, and as a noun, referring to the community, practices and cultures associated with homosexuality. In the 1960s, gay became the word favored by homosexual men to describe their sexual orientation.
https://en.wikipedia.org/wiki/Gay