Backbiter

back·bite  (bkbt)

v. back·bit (-bt), back·bit·ten (-btn), back·bit·ing, back·bites

v.tr.

To speak spitefully or slanderously about (another).

v.intr.

To speak spitefully or slanderously about a person.

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backbiter n.

Thesaurus

Noun

1.

backbiter - one who attacks the reputation of another by slander or libel defamer, libeler, maligner, slanderer, traducer, vilifier depreciator, detractor, disparager, knocker - one who disparages or belittles the worth of something