Bear is gay slang term for those in the bear communities, a subculture in the gay community and an emerging subset of LGBT communities with events, codes and culture specific identity. It also describes a physical type.

Bears tend to have hairy bodies and facial hair; some are heavy-set; some project an image of working-class masculinity in their grooming and appearance, though none of these are requirements or unique indicators. Some bears place importance on presenting a hyper-masculine image; some may shun interaction with men who display effeminate style and mannerisms, although some actually exhibit these traits themselves. The bear concept can function as an identity, an affiliation, and an ideal to live up to, and there is ongoing debate in bear communities about what constitutes a bear. There is also, anecdotally, more acceptance of tattoos and body piercing in the bear community, although this acceptance varies from member to member.

Source: Wikipedia.org