Libelously is an adjective that describes something that is defamatory or slanderous, and synonymously can be replaced by many other words that hold the same meaning. Some of the synonyms for libelously include maliciously, calumniously, unfoundedly, falsely, and slanderously. These words, when used in place of libelously indicate that the statement being made is defamatory and not based in truth. While some of these words carry a stronger connotation than others, they all convey the sense that one is making an untrue or harmful statement about someone else. It is important to avoid making such statements, as they can have serious consequences for both parties involved.