The "w" sound before the vowel and the "y" and "w" after
A semivowel is a quick transition sound that slides into or out of a vowel. Vietnamese writes them with vowel letters (o, u, i, y) that come before or after the main vowel, adding a "w" up front with o/u and sliding off the end with i/y or o/u.
In earlier guides, you learned the 11 single vowels and 3 gliding vowels. Those vowels form the core of the syllable and hold the tone mark.
A semivowel is different. Your mouth passes through it on the way to the main vowel, or slides off it at the end. Vietnamese has two, a "w" and a "y", and both hang off a main vowel. (Linguists call them glides, and when one comes before the vowel it is an on-glide, after it an off-glide.)
Adding a semivowel reshapes the syllable instead of adding a second one:
ta to toa adds a "w" before. ba to bay adds a "y" after. Each stays a single syllable.
When o or u sits between a starting consonant and another vowel, it becomes the "w" semivowel. It rounds your lips for a moment before the main vowel.
| Written | Sound | Before | Examples |
|---|---|---|---|
| o- | "w" as in "water" | a, ă, e | hoatoánhoặckhoẻhoen |
| u- | "w" as in "water" | ê, â, ơ, y, ia/iê (spelled ya/yê) | thuêtuầnhuơtuyhuynhkhuyakhuyên |
The letter you write depends on the vowel that follows. Tap any example to hear it.
After a starting u, the gliding vowels ia and iê are written ya and yê (khuya, khuyên).
A semivowel can also close the syllable. It trails off smoothly instead of cutting your breath like a stop consonant. Vietnamese has two ending semivowels, a "y" and a "w", written with i/y and o/u.
| Written | Sound | After | Examples |
|---|---|---|---|
| -i | "y" as in "boy" | a, o, ô, ơ, u, ư, uô, ươ | tainóitôichơivuingửichuốingười |
| -y | "y" as in "boy" | ă (spelled a), â | taycây |
| -o | "w" as in "cow" | a, e | saođeo |
| -u | "w" as in "cow" | ă (spelled a), â, ê, i, ư, iê/yê, ươ | saucâukêuchịucứuhiểuyêuhươu |
The letter you write depends on the vowel before it. Tap any example to hear it.
The letter you pick marks vowel length:
Same m, but the vowel and its length change with the ending letter.
English speakers often mix up uy and ui. The letters look almost identical, but the semivowel sits at opposite ends.
One spelling looks like ui but the letters split differently: qui. The u in qu functions like the "w" semivowel, so i is the main vowel, not a "y" semivowel. Modern spelling prefers y for that vowel (quy).
qui and quy sound the same because the u is the "w" semivowel and i/y is the main vowel.
Some syllables put the main vowel between two semivowels, a "w" before and a "y" after. They are oai, oay, and uây.
Three rare ones, oao, oeo, and uyu, open and close on a "w" instead. Note that in uyu, the main vowel is the i of iu, written y after the starting u.
The tone mark always rides the main vowel, never a semivowel, so it lands before an ending semivowel (táo, nói), after a starting one (toán), or in the middle when both sides have one (ngoài). That is the tone mark rule from the syllables guide.
Hà Nội keeps every semivowel crisp and distinct, while Sài Gòn smooths them out, flattening complex ending sounds and merging starting "w".
1. Diphthong flattening: Sài Gòn drops the middle "uh" and flattens the syllable into a single vowel plus the ending.
2. The -ưu and -ươu endings: The ư drifts one way in Hà Nội and the other way in casual Sài Gòn.
You can hear the pull in the audio, even if it is not as strong as in everyday talk.
3. The -uyên and -uyêt endings: In casual talk, Sài Gòn drops the starting "w".
Careful recordings keep the "w", so this shift lives in everyday speech rather than in the audio below.
4. The plain "w": Sài Gòn drops the "k" in qu- and the "h" in h- before "w".