Below is an excerpt from a blog I occasionally read called Life Together. I don't know anything about Soma Communities (where the quote comes from), but as far as their definition goes, I'm intrigued. If anyone knows more about Soma, I'd be interested in learning.
What is a Missional Community?:
"A Missional Community consists of a committed core of believers (FAMILY) who live out the mission of God together (MISSIONARIES) in a specific area or to a particular people group by demonstrating the gospel in tangible forms (SERVANTS) and declaring the gospel to others—both those who believe it and those who are being exposed to it (LEARNERS)."