libeler vs backbiter

libeler and backbiter both are nouns.

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

As nouns, libeler and backbiter are synonyms defined as:

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

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

libeler (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