Despite French being my mother tongue, I have trouble with the plural form of an enumeration.

For instance, imagine that I want to describe a plot where there is one (and only one) blue curve, and one red curve. Should I write

Les courbes rouges et bleues...


Les courbes rouge et bleue...

Finally, if there is a rule, does it work only for colors or for all kinds of adjectives?

  • Deux courbes, l'une bleue et l'autre rouge. Sometimes, the structure in French is different than English. = One blue curve and one red curve
    – Lambie
    Jul 8, 2017 at 15:31
  • P.S. @TheCatInTheClock: Bienvenue à French Language Stack Exchange. Vous êtes invité à faire le tour et à visiter le Help Centre, et à continuer à poser de bonnes questions. :)
    – Luke Sawczak
    Jul 8, 2017 at 17:39

3 Answers 3


The plural looks more natural and is what most native French would use:

Les courbes rouges et bleues.

However, the singular is possible and even mandatory in that particular case given the fact it complies with the logic: there is only one red curve and only one blue curve.

Les courbes rouge et bleue.

like we would say, if talking about two and only two couples:

Les couples royal et présidentiel.

See http://bdl.oqlf.gouv.qc.ca/bdl/gabarit_bdl.asp?id=1744

Note also that there are several invariable color adjectives built from nouns, so whatever the number of orange or brown curves, you must always write:

Les courbes orange et marron.

and there are exceptions to these exceptions...:

Les courbes roses et pourpres.

  • In fact, in an other context, native speakers would have a clear intuition about this when singular and plural sound different: « les commentaires *original/originaux et intéressants ». The sentence is agrammatical with the singular original and ok with the plural originaux.
    – GAM PUB
    Jul 8, 2017 at 18:21
  • 1
    @GAMPUB Your example is indeed hurting our ears but that's because it is hard to have precisely two comments, one original but uninteresting, and another interesting but not original. On the other hand Les gouvernements fédéral et provincial is provided as a correct example by the OQLF. I would personally expect Les gouvernements fédéral et provinciaux because there are several provinces, like les pouvoirs central et locaux: there are many locations but there is only one center, so only one central power. A comma can be used to ease the transition: Les pouvoirs, central et locaux.
    – jlliagre
    Jul 8, 2017 at 22:47
  • I would agree if there was a pause (marked by a comma) and the adjectives were adposed rather than attributive...
    – GAM PUB
    Jul 9, 2017 at 16:08
  • @GAMPUB So you disagree with the OQLF who supports the lack of agreement with an non adposed, attributive adjective?
    – jlliagre
    Jul 10, 2017 at 14:32
  • 2
    I'd even believe that, unless the sentence is a generalization, writting “les courbes rouges et bleues” when there's only one red curve and one blue curve is actually wrong by publishing standards. Jul 10, 2017 at 16:52

For what you want to describe, you have to write:

Les courbes rouge et bleue.

As there is one red curve and one blue curve. In this simple case color adjectives behave like normal adjectives so you have to make them agree with the feminine singular.

The other possibilities mean different things:

Les courbes rouges et bleues.

means you are talking about several red curves and several blue ones, but basically the same grammar rules apply.

You could also see:

Les courbes rouge et bleu.

which means that each curve is both red and blue. Here "rouge et bleu" is considered as one complex color and thus there is no agreement.

You can find a source for example in this newspaper article, or if you want something that makes more authority Le français correct by Maurice Grevisse.

  • Thank you for pointing out these subtle differences, and for the references Jul 12, 2017 at 9:40

Although the plural agreement indeed applies here, it would be worth mentioning that compound colour adjectives such as « vert émeraude » and « violet foncé » are invariable, no matter the grammatical number of the noun:

les courbes rouges et bleues

{vs}: les courbes rouges et vert émeraude

On another note: This is not the case with your example where « rouge » and « bleu » are separate colours, but if you are dealing with a single colour made up of multiple words connected by « et », such as « poivre et sel », then the adjective stays singular, even if the noun is in the plural:

les courbes rouges et bleues

{vs}: des cheveux poivre et sel

  • 1
    These are not compound adjectives but rather colour nouns in attributive position.
    – GAM PUB
    Jul 8, 2017 at 18:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.