Louis de Courcillon, known as the abbé de Dangeau (January 1643, in Paris – 1 January 1723, in Paris) was a French churchman and grammarian, best known for being the first to describe the nasal vowels in the French language.
Originally a Protestant of Huguenot origin, he converted to Catholicism in 1668 after a trip to Poland.
[1] He was a younger brother of Philippe de Courcillon de Dangeau.