Le pluriel des noms composés en

In French, words have different "personalities." Some words are flexible and love to change. Others are stubborn and never move. Nouns and adjectives are the flexible ones. They usually agree with the number. If there are many things, they take an s. Verbs, adverbs, and prepositions are the stubborn ones. They stay exactly the same, no matter what. Think of it like a grammar traffic light. Nouns and adjectives get the green light to change. Verbs and prepositions get a red light. When you see a compound noun, look at its parts. Ask yourself: "What is this word's job?" Is it a thing? Is it an action? This simple question solves 90% of your plural problems. It is much easier than memorizing a giant list of words.

1. 1Noun + Noun: Both words usually become plural. They are both "things." Example: un oiseau-mouche (hummingbird) becomes des oiseaux-mouches.
2. 2Adjective + Noun: Both words become plural. Adjectives love to match their nouns. Example: un coffre-fort (a safe) becomes des coffres-forts.
3. 3Verb + Noun: The verb never changes. The noun usually does. Example: un tire-bouchon (corkscrew) becomes des tire-bouchons. The "tire" part comes from the verb tirer (to pull). Actions don't take an s here.
4. 4Noun + Preposition + Noun: Only the first noun changes. Think of it like a sandwich. The first word is the main ingredient. Example: un arc-en-ciel (rainbow) becomes des arcs-en-ciel. You have many arcs, but they are all in one sky.
5. 5Invariant Words: If the word is made of two verbs or a preposition and a noun, it often stays the same. Example: un après-midi (afternoon) becomes des après-midi.

You will use these rules every single day in France. Imagine you are at a local bakery. You want to buy several pains-au-chocolat. You need to know which part of the word to emphasize. Or maybe you are at a hardware store. You are looking for des tournevis (screwdrivers). Even in a job interview, you might talk about des comptes-rendus (reports). Knowing the plural shows you have a great eye for detail. It makes your French sound polished and professional. It is also very helpful when writing emails or texts. Using the correct s makes you look like a pro. Plus, it helps avoid confusion when describing objects to friends.

Don't add an s to everything you see. This is the most common trap. If a word is a verb, leave it alone. In un porte-clés (keyring), the word porte comes from the verb porter (to carry). Even if you have ten keyrings, it is still des porte-clés. Also, watch out for the "one-of-a-kind" rule. In des gratte-ciel (skyscrapers), we don't put an s on ciel. Why? Because the buildings are scraping the sky. There is only one sky! If you add an s, you are scraping multiple universes. That is a bit too much for a Friday afternoon. Always think about the literal meaning of the words.

The biggest mistake is the "S-Overload." People want to put an s on every single word. Remember: verbs are allergic to plural s in compound nouns. Another mistake is forgetting the hyphen. In French, the hyphen acts like glue. If you lose the glue, the word falls apart. Don't forget the middle word in Noun-Prep-Noun structures. People often try to pluralize the last word. In des chefs-d'œuvre (masterpieces), the s goes on chef, not œuvre. It is a "chief of work," not a "chief of works." Think of it as the "Head of the Family" rule. Only the leader gets the new hat.

English is much lazier than French with plurals. In English, we usually just throw an s at the very end. We say "roundabouts" or "mother-in-laws" (though "mothers-in-law" is technically correct). French is more surgical. We go inside the word to find the right spot. It is like comparing a hammer to a scalpel. Also, don't confuse compound nouns with simple adjectives. In des voitures rouges, both words change because it is a simple noun-adjective pair. But in un rouge-gorge (robin), it is a fixed compound. The rules are stricter for these "glued" words. Once they are hyphenated, they follow the compound logic.