French spelling keeps letters that French pronunciation threw away centuries ago. Most final consonants are silent — petit, vous, grand, deux all end in a sound you do not say. Then, under specific conditions, they come back.
That is liaison, and it is a large part of why spoken French sounds like a continuous stream to learners who can read it comfortably.
The consonants change when they return
A silent letter that reappears does not always come back as itself:
| Written | Pronounced as | Example | Sounds like |
|---|---|---|---|
| s, x, z | z | les amis | lay-zami |
| d | t | un grand homme | un gran-tom |
| f | v | neuf heures | neu-veur |
| n | n (nasal carries over) | un ami | un-nami |
| t | t | c'est un livre | say-tun livre |
The s → z shift is the one you will meet constantly, because it governs every plural article. Les, des, ces, mes, vos all end in a z sound before a vowel and in nothing at all before a consonant.
The f → v change is nearly restricted to two phrases: neuf heures and neuf ans. Elsewhere neuf keeps its f.
Liaisons you must make
| Context | Example | Meaning |
|---|---|---|
| Determiner + noun | les enfants, un ami, mon école | the children, a friend, my school |
| Adjective + noun | un petit enfant, les grands arbres | a small child, the tall trees |
| Pronoun + verb | nous avons, ils ont, vous êtes | we have, they have, you are |
| Short preposition + word | en avion, dans une heure, chez elle | by plane, in an hour, at her place |
| est + vowel | c'est une idée | it's an idea |
Two of these carry real information. Ils ont (they have) and ils sont (they are) are distinguished in speech almost entirely by the liaison — il-zon against il-son. Skipping the liaison does not make you sound informal, it makes you ambiguous.
Liaisons that are forbidden
| Context | Example | Note |
|---|---|---|
| After et | et alors | never, in any register |
| Before h aspiré | les héros, en haut | the h blocks it |
| Singular noun + adjective | un enfant intelligent | no link after the noun |
| Before onze, oui, yaourt | les onze joueurs | these behave like consonants |
Les héros and les zéros. This is the example every French teacher uses, and it is a real one. Héros takes h aspiré, so no liaison: les héros is pronounced lay ay-ro. Make the liaison anyway and you produce lay-zay-ro — which is les zéros, the zeros. Curiously the feminine héroïne takes h muet and does liaise, so the rule is per-word rather than per-family.
The two kinds of silent h
Neither is pronounced. They differ in what they permit:
- h muet — the word behaves as though it starts with a vowel. Liaison and elision both happen: l'homme, les hommes (with z), l'hôtel, l'heure.
- h aspiré — the word behaves as though it starts with a consonant. Both are blocked: le héros, la haine, le hibou, le hasard.
There is no way to tell from the spelling. It is a historical residue — h aspiré words tend to come from Germanic and other non-Latin sources — and the practical answer is that dictionaries mark it, often with an asterisk or apostrophe before the entry. If a word begins with h, that is worth checking once and storing with the word.
The optional middle ground
Between required and forbidden sits a group where liaison signals register. After a plural noun, or between a verb and what follows, careful speech tends to liaise and casual speech tends not to:
- Ils sont arrivés — son-tarrivés in a news broadcast, often son arrivés in conversation.
- Des enfants intelligents — the second liaison is optional and more formal.
For a learner the safe strategy is to make required liaisons reliably, avoid forbidden ones, and leave the optional ones alone until you have heard enough French to feel where they belong. Over-liaising is a recognisable learner error — it sounds stilted in the way that never using contractions does in English.
Why this matters for listening
Liaison is usually taught as a speaking rule, but its larger effect is on comprehension. It erases the gaps between words, so vous avez un ami arrives as a single run of sound: voo-za-vay-un-nami. Learners who can read a sentence and cannot recognise it spoken are usually running into this rather than into unknown vocabulary.
The fix is exposure with a text alongside — listen, fail to catch a phrase, read it, then listen again knowing what is there. The words separate quickly once you know which consonants are travelling.
Check French words offline
The free English-French Dictionary shows entries with example phrases, where liaison patterns become visible. Works without a connection.
Open the dictionary appFrequently asked questions
What is liaison in French?
Liaison is the pronunciation of a normally silent final consonant when the following word begins with a vowel sound. The s of les is silent in les livres but pronounced as a z in les amis. It exists to avoid two vowels colliding, and it is one of the main reasons spoken French does not break neatly into separate words.
Is liaison optional in French?
Some liaisons are required, some are forbidden, and a middle group is optional and varies with formality. Required liaisons are non-negotiable — omitting one sounds wrong rather than casual. Optional liaisons are made more often in careful or formal speech, such as news broadcasting, and less often in relaxed conversation.
What is the difference between h muet and h aspiré in French?
Both are silent, but they behave differently. Words with h muet act as if they begin with a vowel, so liaison and elision happen normally: l'homme, les hommes with a z sound. Words with h aspiré block both: le héros, les héros with no liaison. Which words take which is historical and has to be learned individually, though dictionaries mark it.