Invariable adjectives (compound colors, demi, nu)
Summary
A closed set of French adjectives — compound and noun-derived colors, demi, nu, ci-joint/ci-inclus — break the normal agreement rule and stay invariable in specific, learnable conditions.
Explanation
Most French adjectives agree in gender and number with the noun they describe, but a specific, learnable set of adjectives resists this rule entirely or partially. Knowing these exceptions prevents some of the most common advanced-level agreement errors.
Compound color adjectives — two or more words together describing a shade — are always INVARIABLE: des chemises bleu clair (light-blue shirts), des yeux vert foncé (dark-green eyes), des robes rouge vif (bright-red dresses). Because the color is really a compact phrase (bleu + clair), neither word takes an ending, no matter the gender or number of the noun.
Colors that are historically nouns used as adjectives — named after the object whose color they represent — are also invariable: des vestes marron (chestnut-colored jackets), des rubans orange (orange ribbons). The logic is that marron and orange are still felt as nouns ('chestnut', 'an orange'), so they don't inflect like true adjectives. A traditional handful of exceptions have become fully adjectival over time and DO agree normally: rose, mauve, fauve, pourpre, écarlate, and incarnat — hence des joues roses (pink cheeks), with a normal plural -s.
Demi ('half') behaves differently depending on its position. Before the noun, it is joined with a hyphen and stays completely invariable: une demi-heure (half an hour), trois demi-litres (three half-litres) — the -e never appears even before a feminine noun. After the noun, joined with et, demi agrees in GENDER only (never in number, since it always modifies a whole unit that is implicitly singular): une heure et demie (an hour and a half), but midi et demi (noon and a half, masculine because midi is masculine).
Nu ('bare, naked') follows a similar before/after pattern in a few fixed expressions: nu-pieds and nu-tête are invariable when nu comes first, hyphenated, before the noun (aller nu-pieds, to go barefoot). After the noun, nu agrees normally: elle marchait pieds nus (bare feet, agreeing with the masculine plural pieds), tête nue (bare head, feminine singular).
Ci-joint and ci-inclus ('enclosed', 'included') show the same split: placed before the noun or at the head of the sentence, they stay invariable, functioning almost like an adverb: ci-joint les documents que vous avez demandés. Placed after the noun they describe, they agree like ordinary past participles: les documents ci-joints, la facture ci-incluse. The unifying pattern across demi, nu, and ci-joint/ci-inclus is the same: fixed and invariable before the noun, agreeing after it.
Examples
Elle portait des chemises bleu clair et des chaussures vert foncé. — She was wearing light-blue shirts and dark-green shoes. (Compound color adjectives bleu clair and vert foncé stay invariable.)
Nous avons acheté des vestes marron et des rubans orange, mais aussi des écharpes roses. — We bought chestnut-colored jackets and orange ribbons, but also pink scarves. (marron and orange are invariable (noun-derived colors); rose is a traditional exception that agrees.)
Attends-moi une demi-heure ; je serai là à midi et demi. — Wait for me half an hour; I'll be there at half past twelve. (demi-heure: invariable before the noun. midi et demi: agrees in gender only (masculine, since midi is masculine).)
Il est arrivé nu-pieds, puis il est reparti pieds nus dans le jardin. — He arrived barefoot, then went back out barefoot into the garden. (nu-pieds: invariable before the noun. pieds nus: nu agrees after the noun.)
Ci-joint les photos que vous avez demandées. — Enclosed are the photos you requested. (ci-joint invariable when it precedes the noun.)
Vous trouverez les documents ci-joints dans cette enveloppe. — You'll find the enclosed documents in this envelope. (ci-joints agrees (masculine plural) because it follows the noun documents.)
Common mistakes
Elle porte des chaussures marrons.
Elle porte des chaussures marron.
Color adjectives derived from nouns (marron, orange, and compound colors like bleu marine) are invariable: they never agree in gender or number. Write des chaussures marron, not marrons.
Prerequisites
Related rules
adjectivesagreementinvariablecolors