A group of people summoned by a sheriff to aid in law enforcement.
A search party.
A gang involved in crimes such as running guns and illegal narcotics trafficking.
Slang A group of friends or associates.
[Short for Medieval Latin posse comitātūs : Medieval Latin posse, power, body of men (from Latin, to be able; see potent) + comitātūs, genitive of comitātus, county.]