Crossword Genius

It’s said of a number (5)

Ross

I believe the answer is:

vocal

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'it's said' is the definition.
(thesaurus)

I don't understand the remainder of the clue.

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(Other definitions for vocal that I've seen before include "Forthright in argument" , "not instrumental" , "With lots to say" , "Loud in complaining" , "Freely expressing opinions" .)

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