Many of my dictionaries either don’t include this word — meaning an inquisitive person or gossip — or tag it as archaic or obsolete. For a word supposedly dead, it's in rude health, as the recently revised entry in the Oxford English Dictionary confirms.
The ins and outs of celebrity used to be deemed a subject fit only for quidnuncs and checkout girls, but in the 21st century it has attracted serious investigation.
Independent, 10 Sep. 2010.
It’s a fine example of what was originally an obscure (and doubtless somewhat patronising) scholarly in-joke, formed from the two Latin words quid, “what”, and nunc, “now”. It was said to describe a person who was forever asking “What now?” or “What’s the news?”, hence a gossip-monger; it first appeared about 1710.
Nathaniel Hawthorne’s use of it in The House of the Seven Gables in 1851 is typical: “What a treasure-trove to these venerable quidnuncs, could they have guessed the secret which Hepzibah and Clifford were carrying along with them!”.