'maligner' definitions:

Definition of 'maligner'

From: WordNet
noun
One who attacks the reputation of another by slander or libel [syn: defamer, maligner, slanderer, vilifier, libeler, backbiter, traducer]

Definition of 'maligner'

From: GCIDE
  • maligner \ma*lign"er\, n. One who maligns. [1913 Webster]