3 gliding vowels and the spelling flip they trigger
Three vowels glide instead of holding still: ia, ưa, and ua. Each one starts at a high vowel and relaxes into a neutral "uh". When an ending letter arrives, the spelling flips to iê, ươ, and uô, but the sound stays the same.
A gliding vowel, also known as a diphthong, moves from one vowel sound to another inside a single syllable. Vietnamese has a trio that all follow the same recipe: start at a high vowel, then relax.
ia starts at i, ưa at ư, and ua at u, and all three end on a relaxed "uh". Say them slowly and you can feel the slide. At natural speed each one becomes a single smooth vowel.
The 3 gliding vowels, placed by where each one starts. Tap the open form to hear it. Dashed cells are the closed spellings, which never stand alone.
That "uh" is the neutral schwa /ə/, and it's the same in all 3. It's not the short â from the vowels page, which needs an ending of its own.
The glides are built from the plain high vowels. Add a to i, ư, or u, and the vowel stops holding still.
Compare i with ia: bi and bia are different words, and so are chi and chia.
Then ư with ưa: thư and thưa, dư and dưa.
And u with ua: thu and thua, cu and cua.
An ending changes the spelling of the vowel, not its sound. On its own, the glide ends in a (ia, ưa, ua). Once an ending follows, the spelling flips to iê, ươ, and uô.
| Open (no ending) | Example | Closed (ending follows) | Example |
|---|---|---|---|
| ia | chia | iê | chiên |
| ưa | mưa | ươ | mương |
| ua | mua | uô | muôn |
The second letter is the same "uh" you heard in ia, ưa, and ua. It is also why iê, ươ, and uô never stand alone: their spelling means an ending is on the way.
One of the closed forms has a second spelling. When a syllable starts with iê, it is written yê:
Closed forms only take a certain set of endings. They come in three groups:
| Ending type | Endings | Examples |
|---|---|---|
| Nasal | -m, -n, -ng | tiêmđườngbuồn |
| Stop | -p, -t, -c | tiếcướtbuộc |
| Semivowel | -i, -u | hiểungườimuối |
Closed forms never take -nh or -ch. The -i and -u endings are semivowels, covered on the next page.
The tone mark moves with the spelling. Open, it sits on the first vowel (mía, chìa). After the flip, it jumps to the second letter (miếng, chiều). That is the open-then-closed pattern from the tone mark rules.
The open forms (ia, ưa, ua) sound similar across the country. The closed forms are where the regions part ways.
Hà Nội keeps the "uh" full, so muốn opens into two clear parts.
Sài Gòn often lets the "uh" collapse. The three closed forms behave differently depending on the final consonant:
The same words in Hà Nội and Sài Gòn.
Before -i and -u, all three lose the "uh" outright, which the next page covers.