posse: [17] Posse was the Latin verb for ‘be able’. It was a conflation of an earlier expression potis esse ‘be able’; and potis ‘able’ was descended from an Indo-European base *potthat also produced Sanskrit pati- ‘master, husband’ and Lithuanian patis ‘husband’. In medieval Latin posse came to be used as a noun meaning ‘power, force’.
It formed the basis of the expression posse comitātus, literally ‘force of the county’, denoting a body of men whom the sheriff of a county was empowered to raise for such purposes as suppressing a riot. The abbreviated form posse emerged at the end of the 17th century, but really came into its own in 18th- and 19th-century America. => possible, potent
