late 14c. (early 14c. in surnames), "gamekeeper, sworn officer of a forest whose work is to walk through it and protect it," agent noun from range (v.). Attested from 1590s in the general sense of "a rover, a wanderer;" from 1660s in the sense of "man (often mounted) who polices an area." The elite U.S. combat unit is so called from 1942 (organized 1941).