20 French Idioms Explained (And Why They Don't Translate Literally)

Idioms are where a bare dictionary translation breaks down completely — you can know every individual word in a French idiom and still have no idea what it actually means, because the meaning lives in the phrase as a whole, not its parts.

Here are twenty common French idioms, explained in plain terms:

1. Avoir le cafard (to have the cockroach) — to feel down or depressed.
2. Poser un lapin (to put down a rabbit) — to stand someone up, miss an appointment without notice.
3. Coûter les yeux de la tête (to cost the eyes of the head) — to be extremely expensive.
4. Il pleut des cordes (it's raining ropes) — raining very heavily.
5. Avoir un chat dans la gorge (to have a cat in the throat) — to have a frog in your throat, a hoarse voice.
6. Être dans la lune (to be on the moon) — to be daydreaming, not paying attention.
7. Casser les pieds à quelqu'un (to break someone's feet) — to annoy or bother someone.
8. Avoir la pêche (to have the peach) — to feel energetic and in good spirits.
9. Mettre son grain de sel (to put in one's grain of salt) — to give an unsolicited opinion.
10. Appeler un chat un chat (to call a cat a cat) — to speak plainly, call a spade a spade.
11. Chercher midi à quatorze heures (to look for noon at 2pm) — to overcomplicate something simple.
12. Avoir d'autres chats à fouetter (to have other cats to whip) — to have other, more important things to deal with.
13. Tomber dans les pommes (to fall into the apples) — to faint.
14. Sauter du coq à l'âne (to jump from the rooster to the donkey) — to change topic abruptly, mid-conversation.
15. Être sur son 31 (to be on one's 31) — to be dressed up smartly, in one's best clothes.
16. Faire la grasse matinée (to make the fat morning) — to sleep in.
17. Avoir un poil dans la main (to have a hair in the hand) — to be extremely lazy.
18. Donner sa langue au chat (to give one's tongue to the cat) — to give up guessing, admit you don't know.
19. Revenons à nos moutons (let's return to our sheep) — let's get back to the main topic.
20. Ce n'est pas la mer à boire (it's not the sea to drink) — it's not that difficult, don't exaggerate the challenge.

Why idioms matter for real fluency

Textbook vocabulary gets you through exams and formal writing; idioms are what make spoken and casual written French sound genuinely native rather than technically correct but stiff. Native speakers use them constantly, often without noticing.

How to actually learn idioms

Note the context an idiom was used in — the situation usually explains the meaning better than a definition alone — and try reusing it yourself within a few days, since idioms only encountered passively tend to fade quickly.

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