rajah (n.)

also raja, "king or prince in India," 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).