Coquin vs. méchant vs. vilain

In the French language, there are various words to describe levels of naughtiness or mischievous behavior, particularly in children. 'Coquin', 'méchant', and 'vilain' are three terms often used interchangeably, but they carry different connotations and intensities of meaning.

Coquin

This word implies a playful, cheeky, or mildly naughty quality. It is generally affectionate and used for someone who is mischievous in a charming way.
Ne fais pas cette tête, petit coquin!
(Don't make that face, you little rascal!)
Elle a volé un bonbon dans le pot, quelle coquine!
(She stole a candy from the jar, what a little scamp!)

Méchant

'Méchant' suggests a more negative form of behavior. It moves beyond mischievousness into mean-spiritedness or maliciousness. It is stronger than 'coquin' and carries a reprimand.
Cesse d'être méchant avec ta sœur!
(Stop being mean to your sister!)
Il nest pas coquin; il est vraiment méchant quand il bat les autres enfants.
(He's not just naughty; he is really mean when he hits other kids.)

Vilain

'Vilain' strikes a middle ground between 'coquin' and 'méchant'. It indicates bad behavior but not necessarily with harmful intent. It can be used both lightly or seriously depending on context.
Arrête de dessiner sur les murs, cest vilain!
(Stop drawing on the walls, that's naughty!)
Les enfants ont été punis pour avoir dit des mots vilains.
(The kids were punished for saying nasty words.)

Summary

'Coquin', 'méchant', and 'vilain' are all French adjectives used to describe different shades of naughtiness or mischievous behavior in children. 'Coquin' has the most playful and affectionate connotation, implying cheeky or mildly naughty actions. In contrast, 'méchant' conveys a sense of malice or mean-spiritedness. Between these two lies 'vilain', which indicates improper behavior but not as severe as 'méchant'. The choice between these words depends on the nature and severity of the actions being described.