1530s, "the regulation and control of a community," at first essentially the same word as policy (n.1); from Middle French police (late 15c.), from Latin politia "civil administration," from Greek polis "city" (see polis).
Until mid-19c. used in England for "civil administration;" application to "administration of public order, law-enforcement" (1716) is from French (late 17c.), and originally in English referred to France or other foreign nations. The first force so-named in England was the Marine Police, set up 1798 to protect merchandise at the Port of London. Meaning "body of officers entrusted with the duty of enforcing laws, detecting crime, etc." is from 1810.
Police power is the power of a government to limit civil liberties and exercise restraint and compulsion over private rights, especially to advance or protect the public welfare. Police state "state regulated by means of national police" first recorded 1865, with reference to Austria. Police action in the international sense of "military intervention short of war, ostensibly to correct lawlessness" is from 1933. Police officer is attested from 1794, American English. Police station is from 1817.