Raja (also spelled rajah, from Sanskrit राज rāja-) is an Indian term for a monarch, or princely ruler of the Kshatriya varna. The female form, the word for "queen", mainly used for a raja's wife, is rani (sometimes spelled ranee), from Sanskrit राज्ञी rājñī, or ratu, dato, datuk, or datu in Southeast Asia. The title has a long history in the Indian subcontinent and Southeast Asia, being attested from the Rigveda, where a rājan- is a ruler, see for example the (dāśarājñá), the "battle of ten kings".

Read more about Raja:  Etymology, Usage Outside India, Rajadharma