anything that is defamatory or that maliciously or damagingly misrepresents.

What is a Libeler?

Legal Definition of libeler

: a person who makes or publishes a libel.

How do you use libel as a verb?

verb (used with object), li·beled, li·bel·ing or (especially British) li·belled, li·bel·ling. to publish a libel against. to misrepresent damagingly. to institute suit against by a libel, as in an admiralty court.