Syllable Structure • Lesson 3 • Level 2
Medial Glides
How Glides Create Diphthongs and Triphthongs
Medials are optional glide sounds (semivowels) that come between the initial consonant and the nucleus vowel. They create diphthongs like "ua", "ươ", "oa", and triphthongs like "uôi", "ươi". This lesson explains which glides exist, how they combine with nuclei, and the pronunciation of each combination.
What is a Medial Glide?
A medial (also called a glide or semivowel) is a quick transition sound between a consonant and the main vowel. In Vietnamese, medials are optional—not every syllable has one.
Syllable structure with medial:
Initial + MEDIAL + Nucleus + Final + Tone
Without medial:
ba(three) = b + a
cá(fish) = c + á
mạnh(strong) = m + ạ + nh
With medial:
qua(through) = qu + u + a (medial "u")
khoai(potato) = kh + o + ai
thuê(rent) = th + u + ê
⚠️ Important Distinction:
A medial is NOT the same as a nucleus. In "qua(through)", "u" is the medial (glide) and "a" is the nucleus (main vowel). In "tu(study)", "u" is the nucleus (no medial).
The 3 Medial Glides: u, o, ư
Vietnamese has THREE sounds that can function as medials: u, o, and ư. Each creates different diphthongs when combined with nucleus vowels.
U-Medial (w-glide)
/w/ — like "w" in "water"
The "u" medial creates a /w/ sound before the main vowel. It combines with several nuclei:
ua = u (medial) + a (nucleus)
Pronunciation: /wa/ like "wah"
qua(through; past)
mua(buy)
thua(lose)
chua(sour)
vua(king)
đua(race; compete)
Common in native Vietnamese words
uâ = u (medial) + â (nucleus)
Pronunciation: /wə/ — "w" + schwa
quân(army)
muôn(ten thousand) (actually uô, see below)
xuân(spring)
tuần(week)
Often appears in Sino-Vietnamese words
uê = u (medial) + ê (nucleus)
Pronunciation: /we/ — like "way"
quê(countryside; hometown)
thuê(rent; hire)
huê(Hue (city))
khuê(women's quarters)
uô = u (medial) + ô (nucleus)
Pronunciation: /wo/ — like "woe"
muôn(ten thousand)
chuôi(bunch (bananas))
tuổi(age)
khuôn(mold; frame)
thuốc(medicine)
xuống(descend)
uơ = u (medial) + ơ (nucleus)
Pronunciation: /wə/ — "w" + schwa
mươi(ten)
chuối(banana)
tươi(fresh)
lươn(eel)
lưỡi(tongue) (ươ combination)
uy = u (medial) + y/i (nucleus)
Pronunciation: /wi/ — like "we"
uy(prestige)
uy tín(prestige)
quy(rule; return)
thủy(water (Sino))
khuya(late night)
Note: Spelled "uy" but same sound as "ui"
O-Medial
/w/ (variant) — rounded glide
The "o" medial creates combinations that sound like /w/ before the nucleus. Less common than "u" medial.
oa = o (medial) + a (nucleus)
Pronunciation: /wa/ — like "wah"
hoa(flower)
toà(building; court)
khoai(potato)
khoá(lock)
hòa(peace; harmony)
toa(train car)
Important: Tone marks go on "a" in "oa" combinations!
oe = o (medial) + e (nucleus)
Pronunciation: /wɛ/
khoẻ(healthy) (also: khỏe)
khoẹo(difficult)
thoẹt(glimpse)
Rare combination
oai = o (medial) + ai (nucleus)
Pronunciation: /waj/ — "why"
oai(majestic)
ngoài(outside)
khoái(pleasant)
hoài(always; constantly)
This is a TRIPHTHONG: o + a + i (three vowel sounds!)
Ư-Medial
/ɯ/ — unrounded glide
The "ư" medial is rare and appears in only a few combinations:
ưa = ư (medial) + a (nucleus)
Pronunciation: /ɯa/
ưa(like; prefer)
vừa(just; fit)
thừa(surplus)
chưa(not yet)
ươ = ư (medial) + ơ (nucleus)
Pronunciation: /ɯə/
mười(ten)
cười(laugh; smile)
tươi(fresh) (can also be written tuơi)
lưỡi(tongue; blade)
mướn(rent)
nướng(grill)
Important: "ươ" is written together but represents ư (medial) + ơ (nucleus)
ưu = ư (medial) + u (nucleus)
Pronunciation: /ɯu/
ưu(superior; excellent)
ưu tiên(priority)
ưu đãi(preferential)
Mostly in Sino-Vietnamese compounds
Medial Spelling Patterns & Rules
Rule 1: "QU" always includes u-medial
When you see "qu", the "u" is automatically a medial (glide). The next letter is the nucleus.
QU + vowel = u-medial + nucleus
qua(through) = qu + u(medial) + a(nucleus)
quê(countryside) = qu + u(medial) + ê(nucleus)
quý(precious) = qu + u(medial) + y(nucleus)
Compare: No initial, u as nucleus
ua([rare]) = u(nucleus) + a(final)
ủa(huh?) = ủ(nucleus) + a(final)
Rule 2: Tone marks go on the NUCLEUS, not the medial
When a syllable has both a medial and nucleus, the tone mark goes on the nucleus vowel.
✓quá(too; very) — tone on "a" (nucleus), not "u" (medial)
✗*qúa — WRONG! Tone on medial
✓hòa(peace) — tone on "a" (nucleus)
✗*hỏa — tone on "o" (medial) - actually means "fire"! Different word!
✓cười(laugh) — tone on "ơ" (nucleus in ươ)
Exception: oa, oe, uy
In these combinations, the tone CAN go on the second vowel: hoà(peace) or hòa(peace) (both valid), but modern standard prefers tone on "a".
Rule 3: Not all medials combine with all nuclei
There are restrictions on which medial + nucleus combinations are valid:
| Nucleus → Medial ↓ | a | ă | â | e | ê | i/y | o | ô | ơ | u | ư |
|---|---|---|---|---|---|---|---|---|---|---|---|
| u | ✓ | ✗ | ✓ | ✗ | ✓ | ✓ | ✗ | ✓ | ✓ | ✗ | ✗ |
| o | ✓ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ |
| ư | ✓ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ | ✓ | ✗ |
✓ = Valid combination (exists in Vietnamese)
✗ = Invalid (doesn't occur in Vietnamese)
Common Confusions
Confusion 1: ua vs. ưa
ua = u(medial) + a(nucleus)
mua(buy) /mua/
thua(lose) /thua/
Lips rounded throughout
ưa = ư(medial) + a(nucleus)
mứa([rare]) /mɯa/
thừa(surplus) /thɯa/
Lips spread then open
Confusion 2: uô vs. ươ
uô = u(medial) + ô(nucleus)
muôn(ten thousand) /muon/
tuổi(age) /tuoj/
Rounded glide + close-mid back vowel
ươ = ư(medial) + ơ(nucleus)
mười(ten) /mɯəj/
tươi(fresh) /tɯəj/
Unrounded glide + schwa
Minimal pair: muôn(ten thousand) vs. mười(ten)
Confusion 3: When is "u" a medial vs. nucleus?
tu(study) — "u" is the NUCLEUS (no medial)
tua([rare]) — "u" is MEDIAL, "a" is nucleus
qua(through) — "u" (from "qu") is MEDIAL, "a" is nucleus
Rule: If there's another vowel after "u", then "u" is probably the medial!