Muzzler, which refers to someone or something that suppresses or silences others, has several synonyms that could be used interchangeably. For example, "censor," "gag," "oppressor," "silencer," "constrictor," and "restrainer" are all synonyms that produce the same effect of muting someone's voice or controlling their speech. Another synonym is "muffler," which is often used to refer to a device that is designed to reduce the noise produced by an exhaust system or engine. In general, all of these synonyms refer to something or someone that limits or controls the freedom of expression or speech in some way.