Forbidden Liaison

There is a third category of liaison beyond the obligatory and the optional: the forbidden. These are contexts where the conditions for liaison appear to be met — a final consonant followed by a vowel — but where making the liaison is wrong. Native speakers do not make these links. A learner who over-applies liaison here sounds at best hyper-corrected, at worst incomprehensible. The most consequential case, h aspiré, is so subtle that even advanced learners trip over it for years.

This page maps the four major no-go zones, explains the logic behind each, and gives you the lexical lists you cannot derive from rules — they have to be memorized.

Before h aspiré

French has two kinds of h. The letter is silent in both cases — h itself is never pronounced in modern French. But the two kinds behave very differently when it comes to liaison and elision (the dropping of the final vowel of le, la, de, je, etc., before a vowel-initial word).

h muet — silent h, behaves like a vowel

For most words starting with h, the h is purely orthographic, and the word behaves as if it began with the following vowel. Liaison is made, elision is made.

The article le elides to l' before homme, and any preceding consonant would liaise: les hommes → /le.zɔm/, un homme → /œ̃.nɔm/.

/le.zœʁ/ — full liaison.

h aspiré — "aspirated h," behaves like a consonant barrier

A smaller set of words begins with so-called h aspiré. The h is still silent, but it acts as an invisible barrier: liaison is forbidden, elision is forbidden, and the article le/la keeps its full vowel.

Le héros, not l'héros. Articles do not elide; the e of le is fully pronounced.

/le.e.ʁo/, not /le.ze.ʁo/. The plural -s of les stays silent. This is the crux: even though the syntactic context (article + plural noun) demands liaison, the h aspiré blocks it.

The terminology is misleading. Despite being called "aspirated," the h aspiré is not actually pronounced. Centuries ago, in older French and in the Germanic loanwords that gave us many of these forms, the h was a real consonant. Today only the distributional behavior survives: it blocks liaison and elision, even though no sound is articulated.

Which words have h aspiré?

You cannot tell from looking at the spelling. You have to memorize the list — or, more practically, pay attention to whether French speakers say le or l' the first time they use the word. Here are the most common h aspiré words you should know:

Many h aspiré words come from Germanic or other non-Latin sources (English, Frankish, Old Norse, Arabic), which is why they cluster in vocabulary about the household, body, and feelings of an older, less Romance origin. But the rule has spread by analogy and is now arbitrary in modern French.

A counterintuitive case: les héros /le.e.ʁo/, but the singular le héros /lə.e.ʁo/. The feminine héroïne, however, has h muet: l'héroïne /le.ʁɔ.in/, with elision and liaison. Adjective héroïque also takes h muet: un héros héroïque alternates the two patterns. This is one of the quirks you simply have to absorb word by word.

Singular noun + adjective

When a singular noun is followed by an adjective, liaison is forbidden. The plural -s of les amis intelligents is what licenses optional liaison; without it, the link cannot be made.

Soldat anglais is /sɔl.da.ɑ̃.ɡlɛ/, not /sɔl.da.tɑ̃.ɡlɛ/. The final -t of soldat stays silent.

Sujet intéressant is /sy.ʒɛ.ɛ̃.te.ʁe.sɑ̃/, no liaison.

Chocolat amer is /ʃɔ.kɔ.la.a.mɛʁ/. Singular noun, no liaison.

This rule comes from the historical fact that the consonant on the noun and the consonant on the plural -s are different in origin. The plural -s was a true grammatical marker; the silent -t/-d on a singular masculine noun is just an etymological residue. French phonology preserves the productive plural marker in liaison but does not resurrect the residue.

After et

The conjunction et ("and") never liaises with a following word. This rule has no exceptions.

/pjɛʁ.e.an/, not /pjɛʁ.e.tan/.

Vingt et un is /vɛ̃.te.œ̃/. The /t/ you hear is the liaison from vingt to et, not from et to un. After et, hard stop.

/pɛ̃.e.yn.pɔm/. No liaison after et.

The reasoning is historical and somewhat folk-etymological — French grammarians have long treated et as a special syntactic boundary that resists phonological merging. Whatever the cause, the rule is rigid: never liaise after et.

After a singular non-pronominal subject + verb

When a singular noun (not a pronoun) is the subject of a verb, you do not make a liaison from the noun to the verb in modern French.

Frère arrive is /fʁɛʁ.a.ʁiv/, no liaison.

Directeur a annoncé is /di.ʁɛk.tœʁ.a.a.nɔ̃.se/, no liaison from directeur. Note that a annoncé itself, auxiliary + participle, is fully linked.

This is one place where careful, oratorical speech sometimes overrides the rule — in classical recitation you may hear Le directeur-a annoncé. In ordinary speech, no.

Before a fully voweled cardinal number

The cardinal numbers un, huit, onze (and sometimes onzième) start with a vowel sound but resist liaison from a preceding plural article.

/le.ɔ̃z/, not /le.zɔ̃z/. Onze blocks liaison.

In conservative usage, /le.ɥit/, with no liaison; in common modern usage, les huit is sometimes pronounced /le.zɥit/. The traditional rule treats huit as an h aspiré word for liaison purposes; modern speech is mixed.

When un is used as a noun (a number, a label), it behaves as if h aspiré. Le un, le onze. As a determiner before a noun, un ami fully liaises (/œ̃.na.mi/) — that is a different role for the same word.

In some compound and idiomatic expressions

A scattered set of frozen expressions blocks liaison even where syntax would allow it. These are lexicalized.

In nez à nez, you might expect /ne.za.ne/, parallel to les amis. But the expression is a frozen idiom, and no liaison is made.

Before interjections and pauses

A liaison cannot bridge a pause or a punctuation mark in speech. If you breathe, the liaison dies.

Without the hesitation, les enfants sont admits an optional liaison (plural noun + verb — see Optional Liaison); with the pause inserted by euh, even that optional link is impossible. Any pause kills any potential liaison.

Comparison with English

English speakers do not have anything quite analogous to h aspiré. The closest familiar contrast is a vs. an: an apple vs a banana. The choice depends on the following sound, just as French elision depends on whether h is muet or aspiré. But in English the rule is purely phonetic — if the following sound is a vowel, you write an. In French it is lexical — l'homme but le héros, both starting with the same silent h. You have to know each word.

A second analogy: English speakers have lexicalized irregularities like the /ði/ before vowels and /ðə/ before consonants. Most speakers do this without thinking. French h aspiré is similar: a learned, word-by-word distinction that becomes automatic with exposure.

Common Mistakes

A drill text

Read this passage. Every potential liaison is marked: ✓ for liaisons you should make (obligatory), ✗ for liaisons you must avoid (forbidden), ~ for ones that are optional.

Les ✓ enfants ~ ont ✓ entendu le héros ✗ et ✗ ils ✓ ont couru le rejoindre dans le hangar ✗ où il chantait. Le directeur ✗ a applaudi vingt ✓ et un ✗ ans de carrière.

Notice especially:

• Les enfants obligatory (/le.zɑ̃.fɑ̃/)
• enfants ont optional (verbal with auxiliary; many speakers liaise)
• ont entendu obligatory (auxiliary + participle, /tɑ̃.tɑ̃.dy/)
• héros et — no liaison (h aspiré + et)
• et ils — no liaison (after et)
• ils ont obligatory (/il.zɔ̃/)
• hangar où — no liaison (h aspiré on hangar)
• directeur a — no liaison (singular noun + verb)
• vingt et un — liaison from vingt to et (/vɛ̃.te/), then no liaison from et to un
• un ans — variable: traditional usage liaises /œ̃.nɑ̃/ (the determiner role of un dominates), but in counting contexts where un feels noun-like many speakers block it

Key takeaways

Forbidden liaisons are not a matter of register or style. They are categorical bans: h aspiré words refuse liaison and elision; the conjunction et never liaises forward; singular nouns do not liaise to following adjectives in modern French; onze, huit (in conservative usage), and un-as-a-number block liaison from preceding plural articles; and a small set of frozen idioms is lexicalized as no-liaison. The h aspiré category is the one you must build word by word. The article le/la (not l') before a word starting with h is your indicator — when you hear it, mentally tag the word and never liaise to it.