陰口かげぐち
kageguchi

Noun
no-Adjective

1. malicious gossip; backbiting; speaking ill behind someone's back

だれかひと、言いうぶんい分があったら、陰口かげぐちをいわないで、そのひとめんかっていいなさい。
dareka hitoni iibunga attara kageguchio iwanaide sono hitoni mento mukatte iinasai.
If you have a bone to pick with a person, tell it to his face instead of saying things behind his back.
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