Linguistic purism
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 (of which the 1572 Accademia della Crusca set a model example in Europe), and their decisions often have the force of law.
The perceived or actual decline identified by the purists may take the form of a change of vocabulary, syncretism of grammatical elements, or loanwords. The unwanted similarity is often with a neighboring language whose speakers are culturally or politically dominant. The ideal may invoke logic, clarity, or the grammar of classic languages. It is often presented as a conservative measure, as a protection of a language from the encroachment of other languages or of the conservation of the national Volksgeist, but is often innovative in defining a new standard. It is sometimes part of governmental language policy which is enforced in various ways.
The practice opposite of purism, when borrowed words displace native ones, also exists. For example, in English, the native word bookstaff (German: Buchstabe) was replaced by the Latin word letter.