As a deity name
Name 491 of the Surya Sahasranāma — Bhavishya Purana, as taught by Lord Brahma / Sages
As a Hindi name
No reading on this path — this spelling has no entry in our Hindi sources, and no near neighbour is attested there either. We say so rather than invent one.
As a Sanskrit word
Meaning
a king, sovereign, prince, chief (often applied to gods, e.g. to Varuṇa and the other Ādityas, to Indra, Yama &c., but esp. to Soma [also the plant and juice] and the Moon), &c. &c…
Scripturally attestedWhy this matches what you typed
M1 · same meaning "rājñe" is the dative of "rājan" — the same word in a different grammatical case.
Dictionary citations
1. rājan m. (ifc. mostly m(-rāja) , esp. in Tat-puruṣas; f(-rājan, ˚jā or ˚jñī). ; cf. Pāṇ. iv, 1, 28, Sch.) a king, sovereign, prince, chief (often applied to gods, e.g. to Varuṇa and the other Ādityas, to Indra, Yama &c., but esp. to Soma [also the plant and juice] and the Moon), RV. &c. &c.
a man of the royal tribe or the military caste, a Kṣatriya, ĀśvŚr.; ChUp.; Mn. &c. (cf. rājanya)
Caveats
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