Linguistic purism or linguistic protectionism is the prescriptive practice of defining or recognizing one variety of a language as being purer or of intrinsically higher quality than other varieties. Linguistic purism was institutionalized through language academies, and their decisions often have the force of law.

Linguistic prescription, also called prescriptivism or prescriptive grammar, is the establishment of rules defining preferred usage of language. These rules may address such linguistic aspects as spelling, pronunciation, vocabulary, morphology, syntax, and semantics. Sometimes informed by linguistic purism, such normative practices often suggest that some usages are incorrect, inconsistent, illogical, lack communicative effect, or are of low aesthetic value, even in cases where such usage is more common than the prescribed usage. They may also include judgments on socially proper and politically correct language use.