Another user pointed out some poor phrasing in a French sentence I had linked to by saying "C'est du mauvais français."

I am not sure why this uses du rather than de; my impression was that the adjective would cause you to use de. I still oftentimes confuse the proper usage of de/du/de la/de l'/des in cases like this one.

  • Je soupçonne que c'est le résultat du construction «être de» qui indique le qualité de membre d'un groupe, en ce cas le groupe des mots qui constitue «le français»? Voir 2.I.B.6.c de cnrtl.fr/definition/être Commented Jan 14, 2016 at 0:55
  • An adjective can only cause you to use "de" instead of "des," not instead of "du" or "de la."
    – sumelic
    Commented Jan 15, 2016 at 6:02

3 Answers 3


The correct usage would be "C'est du mauvais français", not "de". "français" is here used as something quantifiable and definite (de le => du français, de la langue française, des mots en français, that you can touch and split like du pain), not something abstract like an adverb describing a manner (e.g. c'est de bonne heure = it's early, c'est de bonne guerre = it's fair enough)

Distinction is made (sometimes not easily) between the quantifyable noun and the abstract notion as an adverb. Example given, "c'est de bonne guerre" meaning it's only fair, and "c'est de la bonne guerre" meaning this is some good war.

You are not constrained to use "de" with an adjective + noun, but more often with the adverbial clause.


Le français = la langue française. (l'anglais = la langue anglaise).

this is singular => du (bon / mauvais) français = de la (bonne / mauvaise) langue française.

  • masculin + singulier + indéfini => du or un
  • féminin + singulier + indéfini => de la or une
  • masculin / féminin + pluriel + indéfini => de ou des

du/de la/de = partitif/indénombrable (matière, liquide): du lait, de bons sentiments.

de mauvais français = de mauvaises personnes françaises.

On dirait ce sont de mauvais français (pluriel => ce sont)

  • Surely it would be ce sont des mauvais français ? Commented Jan 14, 2016 at 0:34
  • @Micromégas both are equal. "de" is more stylish. Commented Jan 14, 2016 at 7:29

It's a rule in French, the construct "de le" doesn't exist and is replaced by "du". As opposed to the feminine for which it is "de la".

Je mange de la glace. I eat ice cream

Je mange du pain I eat bread

Je me souviens de la mer. I remember the sea

Je parle du français. I'm talking about French

  • Yes, this is not the point of the question~ I know de le contracts to du. I am asking why le is present at all, why we are saying du mauvais français rather than de mauvais français, as you might when saying J'ai plus d'argent. But thank you anyway. Commented Jan 13, 2016 at 20:17

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