A "closeted" person originally referred only to
lesbians,
gays and
bisexuals who kept their relationship preferences secret. The reason is usually that the person does not want to face the environment's
homophobia. In many places in the world,
coming out of the closet means losing your job, home, family, friends, religious and political memberships. There is often also a real risk of being the victim of violent
hate crime.
In later years it has, often jokingly, come to refer to any person who keeps certain preferences secret, e.g. closet biblioholist, closet cross-dresser
Also see outing