Phrasal verbs.

Is “whisper out” a phrasal verb ?
Exist there a phrasal verb based on “whisper”.
If no, how one can prove it ?

You could improvise such a phrasal verb and say: she whsipered out my name.

So as I understand, your answer is yes and not no.
But what do you mean by “improvise” ? Do you mean that in English one can build verbal constructions on the fly ?

Yes, improvise, as in built on fly. I don't see why not.

I think "whisper out" is already used. Anyway, obviously new phrasal verbs can be made. Language is not set in stone.mugglenet

What is actually a phrasal verb? To my understanding it's a verb which changes its meaning when goes with a certain preposition, so I would translate it to my native language using a completely different word or even several words to describe the action. Examples: run and run into, call and call off, put and put up with, etc. "This is because they actually constitute an idiom". And to make up a new idiom is not that simple. You can improvise and add different prepositions, but it won't automatically turn the verb into a phrasal one. Again: it's only IMHO, and I'm possibly wrong.

I think a phrasal verb is just any combination of a root verb and a preposition that functions as a single verb. ( http://www.sil.org/linguistics/GlossaryOflinguisticTerms/WhatIsAPhrasalVerb.htm )

"Phrasal verbs are IDIOMATIC expressions..."
http://www.usingenglish.com/reference/phrasal-verbs/

"a phrase which consists of a verb in combination with a preposition or adverb or both, the meaning of which is DIFFERENT from the meaning of its separate parts"
http://dictionary.cambridge.org/define.asp?key=59527&dict=CALD

In that case, "whisper out" wouldn't be a phrasal verb since it doesn't have a different meaning from the combination of its component parts.