Soumis par Our Languages blog le 28 août 2020 à 13 h 19
Thank you for your comment, Sandra. This topic can, indeed, be a confusing.
The noun “châtaigne” means “chestnut.” The adjective “châtain,” which comes from “châtaigne,” refers to a light to medium brown colour. So “châtain” is considered a true colour which must agree with the noun it describes. Because “citron” and “noisette” carry the same name as the fruit and nut, respectively, they are considered to be nouns used as adjectives and therefore don’t agree with the noun they describe.