Prévenir vs. avertir vs. mettre en garde

The French language possesses a rich lexicon for conveying the idea of warning someone. While 'prévenir', 'avertir', and 'mettre en garde' can all be translated as 'to warn' in English, they each have nuanced meanings and are used in distinct contexts. Understanding the subtle differences between these words can enhance both language comprehension and communication skills.

Prévenir

This verb generally means to inform someone about something in advance or to take action to prevent something from happening.
Je vais prévenir les voisins de notre fête ce soir.
(I am going to inform the neighbors about our party tonight.)
Prévenir vaut mieux que guérir.
(Prevention is better than cure.)

Avertir

'Avertir' typically implies giving a more formal or serious warning about a particular risk or danger.
Le gouvernement a averti la population d'un risque d'inondation.
(The government has warned the public about a risk of flooding.)
La police a averti les habitants de ne pas sortir pendant le couvre-feu.
(The police warned residents not to go out during curfew.)

Mettre en garde

'Mettre en garde' is often used when cautioning someone more emphatically or protective against a specific danger or bad decision.
Je te mets en garde contre les risques de ce placement financier.
(I'm warning you about the risks of this financial investment.)
L'avocat m'a mis en garde contre la signature de ce contrat précipitamment.
(The lawyer cautioned me against signing this contract hastily.)

Summary

'Prévenir', 'avertir', and 'mettre en garde' have their unique contexts but all share the common ground of involving a form of warning. 'Prévenir' emphasizes prevention and advance notice, 'avertir' is a formal or urgent warning, and 'mettre en garde' suggests a strong caution against potential danger or poor decisions.