Borrowed from Hindi राजा (rājā) and Urdu راجا (rājā), from Sanskrit राजन् (rājan, “king, prince”), from Proto-Indo-Aryan *Hrā́ȷ́ā (“king”), from Proto-Indo-Iranian *Hrā́ȷ́ā, from Proto-Indo-European *h₃rḗǵ-ō, from *h₃rḗǵs (“ruler, king”). Doublet of Rex, rex, and roy.