GENERAL INFO

Fou (m.) / folle (f.) primarily means 'crazy', 'mad', or 'insane'. It functions as an adjective, but can also be used as a noun meaning 'a crazy person'.

USAGE

It describes people or things: *Il est fou.* (He is crazy.) *C'est une idée folle.* (It's a crazy idea.) It's also in common expressions like *un fou rire* (a fit of uncontrollable laughter).

TRAPS

Be careful with agreement: fou (m.s.), folle (f.s.), fous (m.p.), folles (f.p.). A less common form, fol, is used before masculine singular nouns starting with a vowel or silent 'h', e.g., *un fol espoir* (a foolish hope).