mauvaise langue
/məʊˈveɪz ˈlɒ̃ɡ/noun
A vituperative gossip, a scandalmonger. Also (literal ): an evil or malicious tongue.
Origin
Late 19th century; earliest use found in Charlotte Yonge (1823–1901), novelist. From French mauvaise langue from mauvaise, feminine of mauvais bad + langue.