FlexiLingoIn one line
Ninety-nine times out of a hundred you add an
s. The other four rules cover the rest.
The table
| Singular ends in | Plural | on a noun | on an adjective |
|---|---|---|---|
| anything else | + s | livre /livʁ/ → livres /livʁ/ | petit /pə.ti/ → petits /pə.ti/ |
-s · -x · -z | unchanged | choix /ʃwa/ → choix /ʃwa/ | gros /ɡʁo/ → gros /ɡʁo/ |
-eau · -au · -eu | + x | bateau /ba.to/ → bateaux /ba.to/ | beau /bo/ → beaux /bo/ |
-al | -aux | animal /a.ni.mal/ → animaux /a.ni.mo/ | national /na.sjo.nal/ → nationaux /na.sjo.no/ |
-ail | + s — but seven common words take -aux | détail /de.taj/ → détails /de.taj/ | — |
The order does not matter here — a word falls into exactly one of these rows.
And all three pieces move together
| Singular | Plural |
|---|---|
La maison est belle. | Les maisons sont belles. |
Article, noun and adjective — all three. Miss one and the sentence is wrong, even though none of them can be heard.
Exceptions
| Group | Exceptions |
|---|---|
-eu that only takes s /ɛs/ | pneu /pnø/ → pneus /pnø/ bleu /blø/ → bleus /blø/ |
-al that only takes s /ɛs/ | bal /bal/ carnaval /kaʁ.na.val/ festival /fɛs.ti.val/ récital /ʁe.si.tal/ chacal /ʃa.kal/ |
-ail that takes -aux | travail /tʁa.vaj/ → travaux /tʁa.vo/ vitrail /vi.tʁaj/ → vitraux /vi.tʁo/ corail /ko.ʁaj/ → coraux /ko.ʁo/ bail /baj/ → baux /bo/ émail /e.maj/ → émaux /e.mo/ soupirail /su.pi.ʁaj/ → soupiraux /su.pi.ʁo/ vantail /vɑ̃.taj/ → vantaux /vɑ̃.to/ |
| Fully irregular | œil /œj/ → yeux /jø/ ciel /sjɛl/ → cieux /sjø/ |
Compound nouns
| Shape | What gets pluralised | Example | Pronunciation |
|---|---|---|---|
| noun + noun | both | chou-fleur → choux-fleurs | /ʃu.flœʁ/ |
| verb + noun | the noun only | tire-bouchon → tire-bouchons | /tiʁ.bu.ʃɔ̃/ |
| adjective + noun | both | coffre-fort → coffres-forts | /kɔfʁ.fɔʁ/ |
| preposition + noun | the noun only | arc-en-ciel → arcs-en-ciel | /aʁ.kɑ̃.sjɛl/ · /aʁk.zɑ̃.sjɛl/ |
Examples
| English | Singular | Plural |
|---|---|---|
| book | le livre /lə livʁ/ | les livres /le livʁ/ |
| the beautiful house | la belle maison /la bɛl mɛ.zɔ̃/ | les belles maisons /le bɛl mɛ.zɔ̃/ |
| boat | le bateau /lə ba.to/ | les bateaux /le ba.to/ |
| animal | l'animal /la.ni.mal/ | les animaux /le.z‿a.ni.mo/ |
| newspaper | le journal /lə ʒuʁ.nal/ | les journaux /le ʒuʁ.no/ |
| choice | le choix /lə ʃwa/ | les choix /le ʃwa/ |
| eye | l'œil /lœj/ | les yeux /le.z‿jø/ |
| work | le travail /lə tʁa.vaj/ | les travaux /le tʁa.vo/ |
Common mistakes
| ❌ | ✅ | Why |
|---|---|---|
les bateaus | les bateaux | -eau → + x |
les animals | les animaux | -al → -aux |
les choixs | les choix | It already ends in x, so it does not change |
les travails | les travaux | travail is one of the exceptions |
les maisons sont belle | … sont belles | The adjective pluralises too |
les œils | les yeux | Fully irregular |
Where that x came from
a medieval shorthand for `us`
In Old French, cheval pluralised as chevals. That l before a consonant turned into a u → chevaus. And scribes wrote us with an abbreviation mark shaped rather like an x → chevax.
Later, someone forgot what the mark meant and read the x as a real letter — and from then on the u was written out as well: chevaux.
The same sound change turned à le into au and bel into beau. One rule, three places.
And none of it is audible — les livres /le livʁ/ · les bateaux /le ba.to/. This agreement exists on paper only.