Complex sentence: Linguistic purism or linguistic protectionism is the definition of one variety of a language as being purer than other varieties, often in reference to a perceived decline from an ideal past or an unwanted similarity with other languages, but sometimes simply to an abstract ideal.
Split into simpler sentences: Linguistic purism or linguistic protectionism is the practice of defining one variety of a language as being purer than other varieties. The ideal of purity is often opposed in reference to a perceived decline from an "ideal past" or an unwanted similarity with other languages, but sometimes simply to an abstract ideal.