The Collaborative International Dictionary of English v.0.48:
Patrolman \Pa*trol"man\, n.; pl. Patrolmen. One who patrols; a watchman; especially, a policeman who patrols a particular precinct of a town or city. [1913 Webster]WordNet (r) 3.0 (2006):
patrolman n 1: a policeman who patrols a given region [syn: flatfoot, patrolman]