rajah (n.)

also raja, "king or prince in India," ruling either independently or as a feudatory, 1550s, from Hindi, from Sanskrit rajan "king," related to raj "kingdom, kingship," rajati "he rules," and cognate with Latin rex, Old Irish rig "king" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line," thus "to lead, rule"). Related: Rajput, "member of the ruling caste in northern India" (1590s), from Sanskrit rajaputrah "prince," literally "king's son," from putrah "son, boy" (see puerile).