Gay is a noun meaning male homosexual. When used as an adjective, it may be applied to a homosexual of either gender. For example, a lesbian is a gay woman. Most homosexual political organizations use the noun form to refer to gay men and lesbian to refer to gay women.
Gay art and gay spanking art
Erotic gay art is usually M/M and often features muscular and athletic characters. Nudity, partial nudity and fetish clothing, often of black leather, is commonly depicted. Some artists specialize in uniform-like (police or military style) fetish clothing. Erotic gay art may also feature erect penises and depictions of male/male sexuality.
All of these features are also found in gay spanking art. A lot of this art may also be considered BDSM art because of BDSM features such as fetish clothing and/or bondage. For more, see gay spanking art.
The same, more or less, applies to gay spanking literature.