From Sanskrit राजन् (rājan), from Proto-Indo-Aryan *Hrā́ȷ́ā (“king”), from Proto-Indo-Iranian *Hrā́ȷ́ā, from Proto-Indo-European *h₃rḗǵeh₂, from *h₃rḗǵs (“ruler, king”).
राइं • (rāĩ) m