DevNagari or DevaNagari

Devnagari and Devanagari both are the transliterated spellings of देवनागरी. Common perception is that 'Devnagari' is incorrect spelling. It is not.

The brain storming I did, resulted in the following finding!

'व' (v) is not a pure consonant but a semi-vowel! Its pronunciation is in between vowel 'उ' (u) and vowel 'अ' (a). So adding a vowel 'अ' (represented by 'a') is not desperately required after 'v'.

If you ask me which spelling should be preferred, whether 'Devnagari' or 'Devanagari'; my answer will be 'DevaNagari' but not 'Devnagari' [majority wins]. We may use 'Nagari' instead of 'DevaNagari' when we refer it many times as short form.

We write 'DevaNagari' instead of 'Devanagari' to emphasize that 'Nagari' is the important part of the word!