From Longman Dictionary of Contemporary Englishantitrustan·ti·trust /ˌæntiˈtrʌst/ adjective [only before noun] SCLintended to prevent companies from unfairly controlling prices new tougher antitrust laws an antitrust investigationFrom Longman Business Dictionaryantitrustan‧ti‧trust /ˌæntiˈtrʌst/ (also anti-trust) adjective [only before a noun] LAW relating to laws in the US that make it illegal for a company or group of companies to restrict competition, set up a MONOPOLY, or limit another person’s freedom to run a businessThe point of antitrust laws is to prevent restrictions on competition.The US Department of Justice has dropped its anti-trust case against the company.