What is making unfair or untrue statements about a competitor known as?

The term that describes making unfair or untrue statements about a competitor is business defamation. This legal concept encompasses any false communication that damages the reputation of a business or an individual. Business defamation can take various forms, including spoken (slander) and written (libel) statements; however, the overarching term that specifically relates to damaging competitors through false claims is business defamation.

False advertising refers primarily to misleading consumers about the quality or nature of products or services, focusing on the business's own claims rather than those made against competitors. Slander and libel are terms more specifically used in the context of personal defamation and refer to spoken and written defamatory statements, respectively, but do not explicitly capture the competitive aspect that business defamation does. Thus, in the context of competition and reputation among businesses, business defamation is the most appropriate term to describe unfair or untrue statements targeting a competitor.