posse [M17th] The word posse calls to mind the image, familiar from Westerns, of a body of men being recruited by a sheriff and saddling up to pursue outlaws or other wrongdoers. The key element in its meaning is not the pursuing, though, but the fact that the sheriff has empowered this group of people to enforce the law. In medieval Latin posse meant ‘power’, and came from Latin posse ‘to be able’. Posse pre-dated the widespread colonization of the USA, and was first used in Britain during the mid 17th century to mean ‘an assembled force or band’ and specifically ‘the population of local able-bodied men summoned by a sheriff to stop a riot or pursue criminals’. See also power. Possible [LME] comes from the same root, while Latin potentia ‘power’ formed from posse, gives us words such as potent, potentate, and potential (all LME).