Community

John Armstrong defines community like this:

It comes from the Latin communitas and means fellowship/community. The Latin communis means common. A community, as most of us use this term in religious contexts, is thus a smaller social unit within a larger one. It is based upon a friendly association rooted in something believed or held in common. It can take many forms but this is the basic idea. We may attend a church service, to illustrate my point, and never participate in a community.

This is a good definition.

See more on community on John's blog.