A police officer (also called policeman or policewoman, cop, officer or constable) is a warranted law employee of a police force. In most countries, police officer is a generic term not specifying a particular rank. In some, the use of the rank officer is legally reserved for military personnel. Police officers are generally charged with the apprehension of suspects and the prevention, detection, and reporting of crime, protection and assistance of the general public, and the maintenance of public order.
https://en.wikipedia.org/wiki/Police_officer