Semi-vowels (/w/, /ɥ/, /j/)

Summary

French has three semi-vowels (glides): /j/ (the yod, as in hier /jɛʁ/ and fille /fij/), /w/ (as in oui /wi/ and moi /mwa/), and the rounded /ɥ/ (as in lui /lɥi/ and huit /ɥit/). They arise when i, u or ou come before another vowel. The hard one for anglophones is /ɥ/, and the pair /wi/ (oui) vs /ɥi/ (huit) is a key contrast.

Explanation

A semi-vowel (also called a glide or semi-consonant) is a very short vowel-like sound that does not form a syllable of its own but leans onto a following full vowel. French has exactly three: /j/, /w/ and /ɥ/. Each corresponds to one of the three high vowels — /j/ to /i/, /w/ to /u/, and /ɥ/ to /y/ — pronounced so rapidly that it becomes a glide onto the next vowel. Typically they appear when the spellings i, u or ou are followed by another vowel within the same syllable, as in bien, lui and Louis.

The glide /j/, called yod, is the easiest for English speakers because it is the y of 'yes'. It is spelled in several ways: the letter i before a vowel (hier /jɛʁ/, bien /bjɛ̃/), the letter y (yeux /jø/), and very commonly the sequence -ill- or word-final -il after a vowel (travail /tʁavaj/, soleil /sɔlɛj/). One high-value pattern: fille is /fij/ and famille is /famij/. Beware the exceptions ville /vil/, mille /mil/ and tranquille /tʁɑ̃kil/, where -ill- is simply /il/ with no yod; these are treated in the spelling-to-sound rule.

The glide /w/ is the w of English 'we', and it too is familiar. It is spelled ou before a vowel (oui /wi/, Louis /lwi/, ouest /wɛst/) and, crucially, it is the first element of the spelling oi, which is pronounced /wa/: moi /mwa/, roi /ʁwa/, trois /tʁwa/, oiseau /wazo/. The combination oin gives /wɛ̃/, as in loin /lwɛ̃/ and point /pwɛ̃/. So the very common oi is not two separate vowels but a glide plus /a/.

The glide /ɥ/ is the one with no English equivalent, and it is the reason this rule matters. It is the semi-vowel of /y/: to make it, shape your lips for the rounded French u /y/ but glide immediately onto the following vowel. It is spelled u before a vowel and appears in lui /lɥi/, huit /ɥit/, nuit /nɥi/, puis /pɥi/, pluie /plɥi/ and the noun ending -uité. Anglophones tend to replace it with /w/, so nuit comes out like 'nwee'; the correction is to start from the front rounded /y/ (lips rounded, tongue forward as for /i/) rather than from the back rounded /u/.

The single most useful contrast to drill is /wi/ versus /ɥi/. Oui 'yes' is /wi/ — lips rounded and pulled back as for /u/. Huit 'eight' is /ɥit/ — lips rounded but the tongue held forward as for /y/. Say them back to back: oui /wi/, huit /ɥit/; Louis /lwi/, lui /lɥi/. Because /w/ derives from the back vowel /u/ and /ɥ/ from the front vowel /y/, mastering the /u/–/y/ vowel distinction (covered under oral vowels) directly unlocks the /w/–/ɥ/ glide distinction.

Two practical notes. First, whether a high vowel becomes a glide or stays a full syllable can depend on the word and, after certain consonant clusters, French keeps a full vowel plus /j/: compare lion /ljɔ̃/ (glide) with the more deliberate two-syllable pronunciations sometimes heard in careful speech. Second, all three glides are extremely short — do not lengthen them into full vowels. Train the ear on minimal and near-minimal pairs (oui/huit, Louis/lui, and the yod in fille) and imitate native audio, since these contrasts are learned far better by listening than by rule.

Examples

oui / huit — yes / eight (The key contrast: /wi/ (lips back, from /u/) vs /ɥit/ (tongue forward, from /y/).)

lui — him / to him/her (/lɥi/ — the rounded glide /ɥ/; not /lwi/ (that would be Louis).)

la nuit — the night (/nɥi/ — start from front rounded /y/, glide to /i/; avoid the /w/ of 'nwee'.)

hier — yesterday (/jɛʁ/ — the yod /j/, like English y in 'yes'; note the silent h.)

une fille — a girl / a daughter (/fij/ — -ill- after a vowel = /ij/; contrast the exception ville /vil/.)

moi, un oiseau — me, a bird (oi = /wa/: /mwa/, /wazo/ — a /w/ glide plus /a/, not two separate vowels.)

Common mistakes

Prerequisites

• Oral vowels & the e caduc

Related rules

• Oral vowels & the e caduc
• Spelling to sound (ch, gn, -ill-, qu…)
• Consonants (the French r and others)