Jespersen's cycle
Definition - The phenomenon in which a primordial negative particle is augmented by an additional one and then is dropped altogether.

For example, the Old French jeo ne dis evolved into the Modern Standard French je ne dis pas, which in turn led to the Modern Colloquial French je dis pas.

Etymology -
The term originated in the 1979 publication Typology of Sentence Negation by the Swedish linguist Östen Dahl. Dahl coined it to recognize the pioneering work of Otto Jespersen in identifying this language-change pattern.

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