Could be. It's a logical formation of an adverb from the adjective "hushed" (itself formed from the verb "to hush") and as such would apparently mean "more quietly than is usual". If this word isn't in dictionaries, it's because people aren't using it enough.
A "real word" is any word that has meaning for both the person saying it and the person understanding it. Slang words, cant, and nonce-words are all real words even if they are not mainstream. And any word can become mainstream if everyone starts using it.
"Real" is the root word of "really".
Yes. The word "is" is a real word. of course it is.
Yes it is a real word.
Yes, "answer" is a real word.
No, that is not a real word.
no it is not a real word
Yes, it is a real word
It is no where near a real word
yes it is a real word
No ter is not a real word
Shurbby is not a real word.
No, soarn is not (yet) a real word in English.