You read "les amis" and pronounce it [le ami]. A French person says [le-z-ami], with a "z" that comes out of nowhere. That phantom "z" is the liaison - one of the main reasons spoken French sounds nothing like written French. And good news: it follows precise rules.
The liaison consists of pronouncing the normally silent final consonant of a word when the next word starts with a vowel: "les amis" is pronounced [lezami], "nous avons" [nuzavɔ̃], "un petit ami" [œ̃ pətitami]. It is mandatory after determiners (les, des, mes, ces), subject pronouns (nous, vous, ils, elles, on) and adjectives placed before the noun. It is forbidden after "et", after a singular noun and before an aspirated h (h aspiré). In liaison, -s and -x are pronounced [z], -d is pronounced [t].
The principle: a silent consonant that wakes up
In French, most final consonants are silent: "les" is pronounced [le], "petit" is [pəti], "nous" is [nu]. But when the next word starts with a vowel (or a silent h), that sleeping consonant wakes up and attaches itself to the next word:
- "les amis" → [le-z-ami]
- "nous avons" → [nu-z-avɔ̃]
- "un petit appartement" → [œ̃ pəti-t-apaʁtəmɑ̃]
- "un grand homme" → [œ̃ gʁɑ̃-t-ɔm] (the d is pronounced [t]!)
Important detail: consonants sometimes change their sound in liaison. The "s" and the "x" become [z] ("les amis", "deux heures" [døzœʁ]), the "d" becomes [t] ("un grand arbre" [gʁɑ̃taʁbʁ]), and the "f" of "neuf" becomes [v] before "heures" and "ans": "neuf heures" [nœvœʁ].
Mandatory liaisons
These are the ones native speakers always make, without exception. Skipping them is immediately audible.
- Determiner + noun: "les enfants" [lezɑ̃fɑ̃], "des amis", "mes études", "ces objets", "un homme" [œ̃nɔm].
- Subject pronoun + verb: "nous avons", "vous êtes" [vuzɛt], "ils ont" [ilzɔ̃], "elles arrivent", "on est" [ɔ̃nɛ].
- Adjective + noun: "un petit ami" [pətitami], "un gros avion", "les grands espaces".
- After a verb + inverted pronoun: "Est-il là ?" [ɛtil], "Prenez-en" [pʁənezɑ̃].
- After très, trop, plus, bien + adjective: the "s" is pronounced [z]: "très intéressant", "trop aimable".
- In fixed expressions: "tout à l'heure" [tutalœʁ], "de temps en temps" [dətɑ̃zɑ̃tɑ̃], "les Champs-Élysées" [ʃɑ̃zelize], "petit à petit".
The pair to watch first: "ils ont" [ilzɔ̃] (they have) vs "ils sont" [ilsɔ̃] (they are). The difference comes down to a single sound: [z] versus [s]. "Ils_ont mangé" = they ate. "Ils sont mangés"... would mean they were eaten.
Forbidden liaisons
Making a liaison where it's forbidden is just as audible as skipping one. The main cases:
- After "et": "et il est parti" is pronounced [e il], never [etil]. The "t" of "et" NEVER links.
- After a singular noun: "un étudiant intelligent" → no liaison between "étudiant" and "intelligent". The noun-adjective liaison only happens in the plural, and even then it's optional.
- Before an aspirated h (h aspiré): "les héros" [le eʁo], not [lezeʁo] (that would sound like "les zéros" - the zeros - a real source of French jokes). Also: "les haricots", "en haut".
- Before "oui", "onze" and quoted numbers: "les onze joueurs" [le ɔ̃z].
- After "comment" and "quand" in direct questions: "Comment allez-vous ?" is the fixed exception [kɔmɑ̃talevu], but "Comment est-il ?" is pronounced without liaison.
Optional liaisons
In between lies a grey area: liaisons that are possible but not mandatory. The more formal the register, the more of them you make:
- "Je suis allé": [ʒə sɥi ale] in everyday speech, [ʒə sɥizale] in careful speech.
- "des amis anglais": the plural noun + adjective liaison is possible, not mandatory - you'll hear both.
- After "pas": "pas encore" can be [pazɑ̃kɔʁ] or [pa ɑ̃kɔʁ].
Practical advice: at first, stick to the mandatory liaisons. The optional ones will come naturally through listening - and nobody will blame you for not making them.
Liaison or enchaînement: what's the difference?
The two are often confused. The liaison wakes up a silent consonant; the enchaînement moves an already pronounced consonant onto the following vowel:
- Liaison: "les amis" - the "s" of "les" is silent on its own, pronounced [z] before a vowel.
- Enchaînement: "il arrive" → [i-la-ʁiv] - the "l" of "il" is always pronounced, it simply slides onto the "a". Same for "une amie" [y-na-mi], "sept heures" [sɛ-tœʁ].
The consequence for your ear: French words don't start where you expect them to. [ilɑ̃na] is "il en a" cut up differently: three syllables that resemble none of the three written words. That's why you can know every word in a sentence and still not understand it when spoken: the boundaries of written words disappear in the spoken chain.
How to work on the liaison concretely
- Listen while reading. Take a text with its audio and underline every liaison you hear. You'll see the patterns repeat: determiners, pronouns, adjectives.
- Repeat blocks, not words. Don't learn "nous" + "avons" but [nuzavɔ̃] as a single sound unit. Native speakers store these whole blocks.
- Target minimal pairs. Practice with "ils ont / ils sont" [ilzɔ̃]/[ilsɔ̃] and "les uns / les Huns" [lezœ̃]/[le œ̃] (h aspiré: no liaison). Ten minutes a day is enough for your ear to catch the difference.
NB: the liaison with numbers isn't always intuitive: "six" and "dix" are pronounced [sis] and [dis] on their own, [si] and [di] before a consonant ("six mois" [si mwa]), and [siz]/[diz] in liaison ("six ans" [sizɑ̃], "dix heures" [dizœʁ]). Three pronunciations for a single word - French loves that.
