Raja
Raja (/ˈrɑːdʒɑː/; also spelled Rajah, from Sanskrit राजन् rājan-), is a title for a Monarch or princely ruler in South and Southeast Asia. The female form Rani (sometimes spelled ranee) applies equally to the wife of a Raja (or of an equivalent style such as Rana), usually as queen consort and occasionally as regent.
The title has a long history in the Indian subcontinent and South East Asia, being attested from the Rigveda, where a rājan- is a ruler, see for example the dāśarājñá, the "battle of ten kings".
Sanskrit rājan- is cognate to Latin rēx (genitive rēgis) 'King' (as in pre-republican Rome), Gaulish rīx, Gaelic rí (genitive ríg), etc., originally denoting heads of petty kingdoms and city states. It is believed to be ultimately derived from the Proto-Indo-European *h3rēǵs, a vrddhi formation to the root *h3reǵ- "to straighten, to order, to rule". The Sanskrit n-stem is secondary in the male title, apparently adapted from the female counterpart rājñī which also has an -n- suffix in related languages, compare Old Irish rígain and Latin regina.
...
Wikipedia