Solution: Unfounded rumor - NYT Crossword

The [Unfounded rumor] is a CANARD, which is worth mentioning because it’s uncommon enough, but also because it’s a loanword from the French that means “duck,” as in quack rather than stoop, so there’s another animal. Quack also means fake, and it’s possible that the silliness of duck utterances is related to these etymologies. Another story is of an actual hoax perpetrated on the European press in the 19th century that involved cannibalistic ducks — completely fake, fortunately.