Backbiter
Pronunciation : Back"bit`er
Part of Speech : n.
Definition : Defn: One who backbites; a secret calumniator or detractor.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder