Ways to say it
| French | IPA |
|---|---|
| fou | /fu/ |
| délirant | /de.li.ʁɑ̃/ |
The primary way to express being insane is with fou, which can refer to clinical insanity or be used colloquially to mean "crazy" or "wild" in a non-medical sense. The term délirant is also used, but typically in a hyperbolic sense to describe ideas, plans or prices that are completely unrealistic or "insane."
Which one should you use?
While fou covers both clinical insanity and general craziness, délirant is specifically used to describe things like unrealistic plans or extreme prices. For a specific emotional state, the expression fou de rage is used to describe someone driven to an extreme state of anger.
How does it change in a sentence?
The adjective fou changes form based on gender and number: the feminine singular is folle, the masculine plural is fous and the feminine plural is folles.
How do you pronounce it?
/fu/
Did you know?
- There is a curious historical link between the concept of a 'court jester' and the word fou, which some etymologists suggest traces back to the Arabic word for 'elephant', al-fīl.
- To describe someone who is 'insane with love', the French use the phrase fou amoureux, which turns the idea of insanity into a romantic compliment.
- In colloquial French, saying C'est fou! is often used exactly like 'That's crazy!' to express surprise at a piece of news, even if nothing is actually insane.
Examples in context
- Il est devenu fou.He went insane.This sentence is useful for showing the transition into an insane state using fou.Tatoeba #971284 by sacredceltic, translation #8336493 by Amastan
- Il est fou à lier.He is utterly insane.This sentence is useful for expressing the idea of being utterly insane using fou.Tatoeba #2872713 by sacredceltic, translation #5296841 by AlanF_US
- Je ne suis pas fou.I'm not insane.This sentence is useful for a negative statement about being insane using fou.Tatoeba #2661071 by couarail, translation #2248151 by CK
- Ses idées sont folles !His ideas are insane!
- Cette décision est vraiment insensée !This decision is truly insane!
- Il est connu pour son comportement dément.He is known for his insane behavior.
- Elle devient folle à lier !She's acting insane!
- Cette personne est complètement cinglée.That person is completely insane.
- 31 more sentences on Tatoeba
Example conversation
Léa and Lucas are discussing a wild party they heard about.
- LéaTu as entendu parler de cette fête ?Did you hear about this party?
- LucasOui, c'était un truc de fou !Yes, it was something insane!
- LéaLucas, tu es vraiment fou de vouloir y aller.Lucas, you are truly crazy to want to go.
- LucasAllez, ça va être génial !Come on, it's going to be great!
Sources
- Wiktionary, “insane” translations and entries fou, délirant, CC BY-SA 4.0, dump of 2026-09-26.
- Word origins: Wiktionary entries fou, CC BY-SA 4.0.
- Example sentences: Tatoeba CC BY 2.0 FR.
