Good question... I use it, probably cause I studied both Latin and Italian. I know it's uncommon but available in dictionaries. Out of a standard google search, in google scholar, you can find it used in ~600 papers listed, ~180 in last 3 years.
Inside google books, it appears ~2500 times.
I have never heard it, read it or seen it used in any way. This doesn't mean that it doesn't exist – it clearly does, as you found it in a dictionary, but I suggest it is very rare – unless it is used regularly in some academic capacity (which would still make it rare in common usage).