motorcycle club

Noun

 * 1) A group of individuals whose primary interests and activities involve motorcycles.

Usage notes
In the US, the abbreviation "MC" can have a special social meaning from the point of view of the outlaw (a.k.a. one-percenter) subculture, and is usually reserved by them for those clubs that are mutually recognized by other MC clubs. This is indicated by wearing the "MC" patch on the back of a club jacket or vest.