The most common definition of a „bear” is a man who is hairy, has facial hair, and a cuddly body. However, the word „Bear” means many things to different people, even within the bear movement. Many men who do not have one or all of these characteristics define themselves as bears, making the term a very loose one. Suffice it to say, „bear” is often defined as more of an attitude than anything else - a sense of comfort with our natural masculinity and bodies that is not slavish to the vogues of male attractiveness that is so common in gay circles and the culture at large.
chaser
chaserA chaser is generally an average-weight male who is attracted to stocky, chubby, fat or obese males. However, some of the latter also consider themselves as a chaser since it is quite common for either a stocky, chubby, fat or obese male to be attracted to the same.

Otter: a man who is hairy, but is not large or stocky - typically thinner, or with lean muscle. Also typically identified by an energetically playful and flirtatious manner. Slimmer version of a Bear with little pockets of fat like love handles or a tiny gut, but not as lean as a Wolf.
cub
chaserCub - a younger (or younger looking) version of a Bear, typically but not always with a smaller frame. The term is sometimes used to imply the passive partner in a relationship. May not be as hairy but generally has facial hair.
bear
chaserBears 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 and may shun interaction with, and even disdain, men who exhibit effeminacy.

Grizzly Bear: an older Bear, often with a large, wilder beard.

Muscle Bear (Musclebear): a man who identifies as being a Bear, sporting a beard or goatee, hairy body, and is generally muscular. Linebacker build, a mix of muscle and fat.

Polar Bear: is an older bear with white or grey body hair and beard.
gainer
chaserGainer: A person who is sexually turned on by the fantacy or reality of gaining weight, getting fat or being fat. This term is used mainly in the gay male community. I happen to be a gainer!
bears
chaserThe chubby community is a subculture in the gay community. Chubbies are gay men who are overweight or obese. Although there is some overlap between the chubby community and the bear community, the chubby culture is its own distinct subculture and community.