When does S Sound like Z in French?

Have you ever wondered how to pronounce the letter S between two vowels? In French, the letter S has 2 pronunciations in the middle of a word: [s] vs. [z].
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Have you ever wondered how to pronounce the letter S in French? The letter S has 2 pronunciations in the middle of a word and there are rules around this. In this article, you’ll learn how to pronounce the letter S between two vowels in French. You’ll also discover words that have similar spellings but different meanings. A single S or a double SS can change the meaning of a word!

How to pronounce S in the middle of a word?

Master Your French blog covers a wide range of topics related to French pronunciation, listening, culture, and much more. Among many articles, you can learn about French silent letters such as the silent h.

This article is about the specific case when the letter S is between two vowels. To learn more about this topic check the guide to Silent Letters in French.

Watch the right way to pronounce S in French

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Similar words but different meanings

Cousin vs. Coussin

Désert vs. Dessert

Another pair of words in French that have their spelling similar is “désert” and “dessert”. The word “désert” means the desert. As for “dessert” it means dessert in English.

Let’s take the sentence: “Je mange un dessert dans le désert” (I eat a dessert in the desert). You can spot the two words “dessert” and “désert ” in this sentence.

In terms of pronunciation, the S in the word “désert” is pronounced as a /z/ sound because the letter S is between two vowels (e).

On the other hand, “dessert” has a double SS which results the phonetic sound /s/.

desert son z
dessert sound s

Ruse vs. Russe

The word “ruse” in French refers to cunning, a cunning fox. If we take the word “Russe”, which means Russian, it is clear that both words are similar in terms of spelling.

Here is one sentence that has both words: Ce Russe ruse (this cunning Russian). This is another situation where the letter S in “ruse” is between two vowels, the U and the E.

The word “Russe” has a double SS which means that the pronunciation of “Russe” is with the sound /s/. Of course, “ruse” is pronounced with the sound /z/.

rusé sound z
russe sound s

Poison vs. Poisson

Let’s now take a well-known example with the words “poisson” and “poison”. While the word “poisson” means fish, the word “poison” also means poison in English.

The only difference between “poisson” and “poison” is that the former word has a double SS while the latter has a single S. As we saw in the previous example, whenever a S is between two vowels it must be pronounced as /z/. This is the case of “poison”. In order to make a /s/ sound, a word should have a double SS. It is the case of the word “poisson”. So be sure to write “poisson” with a double SS, otherwise you’ll be referring to poison!

Lisent vs. Lissent

A last example in which a single s between two vowels is pronounced /z/ is the word “lisent”:

  • The word “lisent” is the French verb “lire” (to read) conjugated to the present tense in plural.
  • “Lisent” is very close in terms of spelling to “Lissent” which means to smooth in English.

Now, you know that “lisent” is pronounced with /z/ while “lissent” is pronounced with the sound /s/.

Pronunciation and exceptions with the letter S

There are some words that are written with a single S but are pronounced with the sound /s/. Let’s see some of these exceptions.

Exception 1: After the prefix "R"

The word “resaler” has a single S but this s is pronounced as /s/ (not as /z/). Resaler means to add more salt.

Exception 2: After the prefix "A"

“Asymétrie” is pronounced with an /s/ regardless of having the letter S between two vowels. Asymmetry is the meaning of “asymétrie” in English.

Exception 3: After the prefix "Para"

After the prefix “para”, the letter S is pronounced as /s/ even if it is located between two vowels. Here is one example “parasol” (beach umbrella).

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