L'Élision: l'arbre, j'aime

If you have ever wondered why French books are full of apostrophes — l'homme, j'aime, qu'il dit, d'accord — you have already met elision. Elision is the rule that replaces the final vowel of a small set of one-syllable words with an apostrophe whenever the next word begins with a vowel sound. It is mandatory in writing and in speech: skipping it produces utterances that no native speaker ever makes, and that French children correct for in their reading from age six.

Elision is one of two foundational orthographic processes that bind French words to one another at the phonological seam. The other is contraction — the mandatory fusion of à and de with le and les into au, aux, du, des. Both processes exist for the same reason: French dislikes the collision of two vowels across a word boundary, and even more dislikes the sequence preposition + article when each member is a single weak syllable. Elision deletes a vowel; contraction fuses two words into one. Together, they are the most-frequent grammatical rules in the language. You apply them dozens of times in any normal conversation.

This page lists every word that elides, when, and why — and clarifies how elision interacts with contraction at the boundary where the two rules meet.

What gets elided, and where

Elision applies to a closed set of short, function-word vowels. The list is finite. Memorize it.

A few patterns jump out:

1. The vowels that elide are e, a, and i. Other vowels (u, o) do not elide.
2. Ce only elides before forms of être: c'est, c'était, c'eût été. Not c'arrive; that would be ça arrive.
3. Si only elides before il and ils. Si elle, si on, si arrive never elide: si elle vient, not /s'elle vient/.
4. The compound conjunctions parce que, lorsque, puisque, quoique, jusque lose only the final e of que / jusque: parce qu'il, not /parc'qu'il/.

Elision is mandatory

Unlike English contractions (I am → I'm), which are optional and tied to register, French elision is obligatory. It is enforced both in writing and in speech. Saying je aime instead of j'aime is not informal; it is ungrammatical. A native speaker hearing it will register it as a learner error or a typo.

The reason is phonological: French has a strong dispreference for two adjacent vowels across a word boundary. Wherever a function-word vowel could collide with the next word's initial vowel, elision applies automatically — the speaker does not "choose." The same principle drives liaison (where a normally-silent consonant resurfaces to fill a vowel-vowel gap) and contraction (where two words fuse into one).

Elision and h aspiré

The one place where elision does not apply despite a phonological vowel start is before h aspiré. H muet (the silent h of homme, heure, histoire) behaves as a vowel and triggers elision: l'homme, l'heure, l'histoire. H aspiré (the silent h of héros, haine, honte) blocks elision as if the word started with a real consonant: le héros, la haine, la honte.

The two types of h look identical in spelling. Distinguishing them is purely a matter of memorizing which word belongs to which set. See the dedicated H Aspiré vs H Muet page for the full list and the diagnostic test.

Contraction: where elision meets prepositions

Contraction is a different mechanism, but it shares elision's logic. When the prepositions à and de meet the definite articles le and les, French fuses them into single forms — au, aux, du, des. This is mandatory and irreversible: the non-contracted forms /à le, à les, de le, de les/ do not exist in modern French.

The non-contracted feminine forms à la and de la stay as they are: à la maison, de la viande. The reason is partly phonological — au is a single vowel /o/, fused from à + le; à la has a consonant between the two vowels, so there is nothing to fuse. Functionally, au, aux, du, des feel like single words to a French speaker; à la, de la feel like two.

For the full mechanics — including auquel/duquel, country names, and verb constructions that take à or de — see The Contractions au, aux, du, des.

When elision and contraction collide

Both rules apply to the same prepositions, but in different environments. The order is:

1. Contraction first, when the noun starts with a consonant: je vais au marché (à + le → au).
2. Elision instead, when the noun starts with a vowel or h muet: je vais à l'école (à + l').

The combined effect: à and de each have three surface forms depending on what follows.

Notice that à l'école and de l'école are the result of elision applying to the article l', not contraction. Contraction never produces l' — that is purely the domain of elision. This matters because it explains why feminine vowel-initial nouns and masculine vowel-initial nouns look identical in this slot: they both go through the same elision path.

What does NOT elide

A few near-misses are worth flagging.

Possessive determiners mon, ma, mes, ton, ta, tes, son, sa, ses, notre, votre, leur, leurs never elide. Their final vowels are full (not weak schwa-like), and they do not collapse against the next word. Mon ami stays mon ami — but liaison applies: /mɔ̃.na.mi/.

The pronoun tu does not elide in standard written French. Tu as is tu as, not /t'as/. However, in casual spoken French t'as is universal and is increasingly written in informal texts (chat, lyrics, dialogue). It is non-standard in formal writing but completely natural in speech. (formal: tu as fait quoi ?; informal: t'as fait quoi ?)

The pronoun le as direct object does not elide before a verb in modern French. Je le vois /ʒə.lə.vwa/, never /ʒə.l.vwa/. The schwa /ə/ may be dropped in fast speech, but the orthographic *le is preserved.

Two-syllable function words like cela, que (when stressed), and quelle do not elide.

How French speakers think about it

For a native speaker, elision and contraction are not "rules" applied step by step. They are baked into the lexicon. The form l'arbre is stored as a phonological unit /laʁbʁ/, just as au cinéma is stored as /o.si.ne.ma/. A French child learns these forms holistically and never separates the article from the noun in production — which is why French children learning to write often misanalyse the article boundary, writing lavion (for l'avion) or un navion (for un avion) before they sort out the spelling conventions.

For an English speaker, this is unfamiliar territory. English contractions (I'm, can't, don't) are optional, tied to informality, and orthographically marked as fusions. French elision is obligatory, register-neutral, and so embedded in the language that the unelided form is simply ungrammatical. Je aime is not "more formal"; it is not French.

Internalize this from day one. When you see aime — or any vowel-initial verb — and you want to put je in front of it, your hand should write j' without conscious thought.

Common Mistakes

These are the errors English speakers and other beginners make most often.

Key takeaways

• Elision replaces the final vowel of le, la, je, me, te, se, ne, ce, de, que, jusque, lorsque, puisque, quoique, parce que, si (only before il, ils) with an apostrophe before a vowel or h muet. It is mandatory in writing and in speech.
• Contraction fuses à + le → au, à + les → aux, de + le → du, de + les → des. It is also mandatory; the unfused forms do not exist.
• À la, de la and à l', de l' are not contractions — feminine la does not contract, and l' is the result of elision.
• Si elides only before il and ils, never before elle, on, ils' alternatives, or any other word.
• Ce elides only before forms of être (c'est, c'était, c'eût été).
• Tu does not elide in standard French, though t'as, t'es, t'aimes are universal in casual speech.
• H aspiré blocks both elision and liaison; h muet allows both. The difference is invisible — you must learn each h-initial word's category individually.