Which French adjectives are invariable?

Colours taken from nouns (orange, marron, crème), compound colours (bleu clair, vert foncé), borrowings (chic, snob, cool), adjectival phrases (bon marché), and adjectives used as adverbs (coûter cher, parler fort). Demi, nu, and ci-joint are invariable only in front of the noun.

Why doesn't orange agree in French?

Because it's still the name of a fruit. Des rideaux orange means curtains the colour of an orange, and the fruit isn't plural. Rose, by contrast, has been a full adjective for centuries, so des rideaux roses does take an -s.

Is it des gens sympa or des gens sympas?

Des gens sympas. Sympa is a shortening of sympathique, and it has picked up a plural -s while resisting a feminine -e: une fille sympa, des filles sympas. It's the one abbreviation in this family that partly agrees.

Why is it une demi-heure but une heure et demie?

Position decides it. Before the noun, demi is adverbial, hyphenated, and frozen. After the noun it's a genuine adjective and agrees in gender, though never in number: deux heures et demie, not demies.

Do adjectives used as adverbs ever agree?

No. In parler fort, coûter cher, sentir bon, and travailler dur, the word is describing the action rather than the subject, so there's nothing to agree with. Ils parlent fort stays fort however many people are talking.

French grammar · Intermediate

Invariable Adjectives in French: The Ones That Never Change

Written by Camille Laurent, Lead French Curriculum Editor · Reviewed May 2026

A few French adjectives never take gender or number endings. Most of them aren't really adjectives underneath: they're nouns, compounds, loanwords, or adjectives doing an adverb's job, and none of those word classes agrees in French.

Elle a acheté des rideaux orange et des coussins marron.

She bought orange curtains and brown cushions.

What it is

French agreement is so consistent that the exceptions stand out. Every invariable adjective is invariable for a reason, and once you know the reason you can predict the behaviour of new ones instead of memorising a list.

des gants marron, une jupe bleu clair, des vestes chic — brown gloves, a light blue skirt, stylish jackets.

How to spot it

Ask what the word was before it became an adjective. If it was a noun, a phrase, or a foreign word, it probably won't agree.

des yeux marron — brown eyes (marron is a chestnut)
des chaussures bon marché — cheap shoes (bon marché is a phrase)
une soirée très chic — a very stylish evening (a loanword-style adjective)
Ces livres coûtent cher. — These books are expensive. (cher is an adverb here)

The pattern is consistent: French only puts endings on things it recognises as adjectives, and a noun in adjective clothing is still a noun.

Invariable Adjectives Quick Reference

The invariable families and why they don't agree

Type	Examples	Sample phrase	Reason
Colours from nouns	orange, marron, noisette, crème	des gants marron — brown gloves	still a noun underneath
Compound colours	bleu clair, vert foncé, bleu marine	des yeux bleu clair — light blue eyes	the whole phrase is frozen
Borrowed adjectives	chic, snob, cool, sexy	des vestes chic — stylish jackets	no French endings to take
Shortened words	sympa, super, extra	des gens sympas — nice people	sympa takes -s but never -e
Adjectival phrases	bon marché, haut de gamme	des produits bon marché — cheap products	a phrase, not a single word
demi before a noun	demi	une demi-heure — half an hour	adverbial in that position
Adjectives used as adverbs	cher, fort, bon, dur, droit	Ils parlent fort. — They speak loudly.	adverbs never agree
ci-joint before a noun	ci-joint, ci-inclus	Ci-joint la copie. — Please find the copy attached.	adverbial before, adjectival after

Common Invariable Adjectives Examples in French

The main groups, with the agreeing versions alongside for contrast:

Colours That Are Really Nouns

des chaussures marron: brown shoes
une écharpe orange: an orange scarf
des murs crème: cream walls
des rideaux roses: pink curtains

The last one agrees: rose has been an adjective for long enough that French has naturalised it. So have mauve, pourpre, fauve, and écarlate.

Compounds and Phrases

une robe bleu clair: a light blue dress
des voitures haut de gamme: top-of-the-range cars
des billets bon marché: cheap tickets
des chaussettes vert foncé: dark green socks

As soon as a second word joins the adjective, the pair behaves as one block and no endings appear on either half.

Borrowings and Abbreviations

une soirée chic: a stylish evening
des gens snob: snobbish people
des voisins sympas: nice neighbours
des idées super: great ideas

Sympa is the odd one out: it takes an -s in the plural but never an -e, because it's a shortening of sympathique.

Adjectives Working as Adverbs

Ces valises coûtent cher.: These suitcases are expensive.
Les enfants parlent fort.: The children are talking loudly.
Ces fleurs sentent bon.: These flowers smell good.
Elles travaillent dur.: They work hard.

Here the word is modifying the verb, not the subject, so there's nothing for it to agree with.

Why These Adjectives Don't Agree

Every case comes back to the same question: is the word really an adjective at this moment?

A Noun in Disguise Stays a Noun

Marron, orange, citron, and crème name things. Des yeux marron is shorthand for eyes the colour of a chestnut, and the chestnut isn't plural, so nothing takes an -s.

des chaussures marron et des gants noisette

brown shoes and hazel gloves

Was it a thing? Then no endings.

Compounds Freeze

Adding a second word turns the colour into a unit. Bleu clair is not bleu that happens to be clair; it's a single term, and units don't inflect their parts.

une chemise vert pâle et une cravate bleu marine

a pale green shirt and a navy blue tie

Two words → zero endings.

Loanwords Have No French Endings

Chic, snob, cool, and sexy arrived without a French adjective paradigm and largely haven't acquired one. Usage is drifting — you'll see des looks cools in the press — but the conservative forms remain invariable.

des vêtements très chic

very stylish clothes

Borrowed → usually unchanged.

An Adjective Modifying a Verb Is an Adverb

Coûter cher, parler fort, sentir bon, travailler dur, voir grand: in each case the word describes the action, not the subject. Adverbs are invariable in French without exception.

Ces tableaux valent cher.

These paintings are worth a lot.

Describing the verb → no agreement.

Position Can Decide the Behaviour

Demi, nu, and ci-joint are invariable in front of the noun and agree after it. The front position is adverbial and the rear position is adjectival, so the same word behaves in two ways.

une demi-heure, deux heures et demie

half an hour, two and a half hours

Before → frozen. After → agrees.

Common Mistakes with Invariable Adjectives

Incorrect: des chaussures marrons — brown shoes

Correct: des chaussures marron — brown shoes

Marron is the noun for a chestnut being pressed into service as a colour. Nouns don't agree with other nouns, so no -s appears.

Incorrect: une jupe verte foncée — a dark green skirt

Correct: une jupe vert foncé — a dark green skirt

Once a colour picks up a modifier, the whole phrase freezes in the masculine singular. Both halves lose their endings, not just the second one.

Incorrect: Ces valises coûtent chères. — These suitcases are expensive.

Correct: Ces valises coûtent cher. — These suitcases are expensive.

Cher here describes how much they cost, so it's modifying the verb rather than the suitcases. Adverbs are invariable in French.

Incorrect: une demie-heure — half an hour

Correct: une demi-heure — half an hour

Demi is invariable in front of the noun and takes a hyphen. It only agrees when it comes after: une heure et demie.

The Words That Depend on Where They Stand

Three items agree in one position and not in another, which makes them the hardest part of this topic.

Demi, mi, and semi

Before the noun, demi is joined by a hyphen and never changes. After the noun, it agrees in gender but stays singular. Mi and semi are always invariable and always hyphenated.

une demi-journée: half a day
trois heures et demie: three and a half hours
un kilo et demi: a kilo and a half
à mi-chemin: halfway

The agreement after the noun is with the noun itself: heures is feminine, so demie; kilo is masculine, so demi.

Nu before and after

The same pattern applies to nu. Hyphenated and invariable in front, fully agreeing behind.

Il marche nu-pieds.: He's walking barefoot.
Elle avait les pieds nus.: Her feet were bare.
nu-tête: bare-headed

Nu-pieds and pieds nus mean the same thing and differ only in structure, which makes them a neat illustration of the rule.

Ci-joint in correspondence

In business writing, ci-joint is invariable when it opens the sentence or precedes the noun, and agrees when it follows one.

Ci-joint la facture.: Please find the invoice attached.
Veuillez trouver la facture ci-jointe.: Please find the attached invoice.
Ci-joint les documents demandés.: Attached are the requested documents.

Ci-inclus behaves identically. Both are formal and belong to letters and emails rather than speech.

Invariable Adjectives FAQs

Which French adjectives are invariable?: Colours taken from nouns (orange, marron, crème), compound colours (bleu clair, vert foncé), borrowings (chic, snob, cool), adjectival phrases (bon marché), and adjectives used as adverbs (coûter cher, parler fort). Demi, nu, and ci-joint are invariable only in front of the noun.
Why doesn't orange agree in French?: Because it's still the name of a fruit. Des rideaux orange means curtains the colour of an orange, and the fruit isn't plural. Rose, by contrast, has been a full adjective for centuries, so des rideaux roses does take an -s.
Is it des gens sympa or des gens sympas?: Des gens sympas. Sympa is a shortening of sympathique, and it has picked up a plural -s while resisting a feminine -e: une fille sympa, des filles sympas. It's the one abbreviation in this family that partly agrees.
Why is it une demi-heure but une heure et demie?: Position decides it. Before the noun, demi is adverbial, hyphenated, and frozen. After the noun it's a genuine adjective and agrees in gender, though never in number: deux heures et demie, not demies.
Do adjectives used as adverbs ever agree?: No. In parler fort, coûter cher, sentir bon, and travailler dur, the word is describing the action rather than the subject, so there's nothing to agree with. Ils parlent fort stays fort however many people are talking.