defamer vs backbiter

defamer and backbiter both are nouns.

Word	Noun	Adjective	Verb	Adverb
defamer	Yes	No	No	No
backbiter	Yes	No	No	No

As nouns, defamer and backbiter are synonyms defined as:

defamer and backbiter: one who attacks the reputation of another by slander or libel

Other synonyms of defamer include libeler, maligner, slanderer, traducer, vilifier.

defamer (noun)	backbiter (noun)
one who attacks the reputation of another by slander or libel	one who attacks the reputation of another by slander or libel