noun

1. Historical
   in full posse comitatus posse co·mi·ta·tus (käm′ə tāt′əs)
   1. the body of men required, upon being summoned, to assist the sheriff in keeping the peace, pursuing felons, etc.
   2. a band of men, usually armed, so summoned
2. any body of persons armed with legal authority
3. ☆
   1. in the Old West, a group assembled to hunt for criminal fugitives
   2. a search party
4. Slang
   1. a gang, esp. one engaged in selling drugs
   2. any group of people, as of a person's friends and associates

Etymology: ML, short for posse comitatus, power of the county < L posse, to be able (see potent) + comitatus, county < comes, a count