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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/khaphanspace/gonhanh.org/llms.txt

Use this file to discover all available pages before exploring further.

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Overview

Vietnamese (Tiếng Việt) uses the Latin-based Quốc Ngữ writing system with extensive diacritics to represent tones and special vowels. Understanding this system is essential for implementing Vietnamese input methods.

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Alphabet

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Vietnamese Alphabet (29 letters)

UppercaseLowercaseName
Aaa
Bbbê
Ccxê
Dddê
Eee
Gggiê
Hhhát
Iii
Kkca
Lle-lờ
Mmem-mờ
Nnen-nờ
Ooo
Pppê
Qqcu/quy
Rre-rờ
Ssét-sì
Tttê
Uuu
Vvvê
Xxích-xì
Yyi dài
The letters F, J, W, Z are not part of the Vietnamese alphabet but appear in loanwords and foreign names.

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Vowel System

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Simple Vowels (12)

PositionFrontCentralBack
Highiưu
Mid-highêơô
Mid-loweâ, ăo
Lowa

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Diphthongs (27 patterns)

First vowel is glide, second is main vowel:
PatternIPAExamplesNotes
ia/iə/kia, mía, líaOpen vowel
iê/iə/tiên, kiên, liênCompound vowel
ua/uə/mua, cua, luaOpen vowel
uô/uə/muốn, cuốn, luônCompound vowel
ưa/ɨə/mưa, cửa, lửaOpen vowel
ươ/ɨə/mương, người, đượcCompound vowel
First vowel is main, second is semi-vowel ending:
PatternIPAExamples
ai/aj/hai, mai, tai
ay/aj/hay, may, say
ây/əj/đây, cây, mây
oi/ɔj/coi, đói, nói
ôi/oj/tôi, hội, đối
ơi/əːj/bơi, chơi, rơi
ui/uj/núi, dui, cúi
ưi/ɨj/gửi, lửi
iu/iw/dịu, kíu, tiu
PatternIPAExamples
ao/aw/cao, sao, nao
au/aw/sau, mau, dâu
âu/əw/đâu, câu, sâu
êu/ew/kêu, rêu, nêu
eo/ɛw/keo, theo, treo
ưu/ɨw/lưu, hưu, ngưu
First vowel is glide (not main vowel):
PatternIPAGlideMainExamplesCondition
oa/wa/oahoa, toa, loaAfter consonant
oă/wa/oăxoắn, loắt, hoặcAfter consonant
oe/wɛ/oekhoe, xoe, toeAfter consonant
uê/wə/uêhuệ, tuệ
uy/uj/uyquy, huy, tuy
uâ/wə/uâluân, tuân, quânRare
Special case: “ua”
  • After “q” (qua, quả): u is glide, a is main → tone on a
  • Open syllable without “q” (mua, cua): u is main, a is semi-vowel → tone on u
  • Closed syllable with final (chuẩn, thuận): u is glide, â is main → tone on â

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Triphthongs (10 patterns)

PatternIPAStructureExamplesTone position
iêu/iəw/i + ê + utiêu, kiều, liêuê (middle)
yêu/iəw/y + ê + uyêu, yếuê (middle)
oai/waj/o + a + ingoài, loại, hoàia (middle)
oay/waj/o + a + yxoay, ngoáya (middle)
oeo/wɛw/o + e + okhoèo, ngoẹoe (middle)
uây/uəj/u + â + ykhuấy, quậyâ (middle)
uôi/uəj/u + ô + icuối, tuổi, buổiô (middle)
ươi/ɨəj/ư + ơ + imười, tươi, lườiơ (middle)
ươu/ɨəw/ư + ơ + urượu, hươu, bướuơ (middle)
uyê/uiə/u + y + êkhuyên, chuyên, quyềnê (final)

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Consonant System

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Initial Consonants

ConsonantIPAPositionMannerExamples
b/ɓ/LabialImplosiveba, bé
c/k/VelarStopca, có
d/z/ (N) /j/ (S)AlveolarFricativeda, dê
đ/ɗ/AlveolarImplosiveđi, đó
g/ɣ/VelarFricativegà, gỗ
h/h/GlottalFricativehoa, hát
k/k/VelarStopkéo, kê
l/l/AlveolarLateralla, lá
m/m/LabialNasalma, mẹ
n/n/AlveolarNasalna, nói
p/p/LabialStoppin (loan)
q/k/VelarStop (always qu)qua, quê
r/z/ (N) /r/ (S)AlveolarTrill/Fricativera, rồi
s/s/AlveolarFricativesa, sao
t/t/AlveolarStopta, tôi
v/v/LabiodentalFricativeva, về
x/s/AlveolarFricativexa, xanh

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Final Consonants

ConsonantIPAExamples
c/k/các, học
ch/c/ách, ích
m/m/cam, tâm
n/n/can, tân
ng/ŋ/cang, tang
nh/ɲ/anh, inh
p/p/cập, tập
t/t/cát, tất
k/k/Ethnic minority namesĐắk Lắk

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Orthographic Rules

C before: a, ă, â, o, ô, ơ, u, ư
K before: e, ê, i, y
Q always with U: qu

Examples:
✓ ca, cô, cu, căn, cơm
✓ kẻ, kê, ki, ký
✓ qua, quê, quy, quả
✗ ce, ci (must use: ke, ki)
✗ ka, ko (must use: ca, co)

G before: a, ă, â, o, ô, ơ, u, ư
GH before: e, ê, i

Examples:
✓ gà, gỗ, gương
✓ ghe, ghế, ghi
✗ ge, gi (if /ɣ/ sound, must use: ghe, ghi)
Note: "gi" is a separate consonant /z/, not /ɣ/

NG before: a, ă, â, o, ô, ơ, u, ư
NGH before: e, ê, i

Examples:
✓ ngày, ngồi, ngủ, ngưng
✓ nghe, nghề, nghỉ, nghĩa
✗ nge, ngi (must use: nghe, nghi)
✗ ngha, ngho (must use: nga, ngo)

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Tone System

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Six Tones

#NameMarkIPAContourExampleDescription
1Ngang(none)/ma˧/˧ (33)maLevel, mid
2Huyền`/ma˨˩/˨˩ (21)màFalling, low
3Sắc´/ma˧˥/˧˥ (35)máRising, high
4Hỏỉ/ma˧˩˧/˧˩˧ (313)mảDipping
5Ngã~/ma˧˥ˀ/˧˥ˀ (35ˀ)mãRising, glottalized
6Nặng̣/ma˧˩ˀ/˧˩ˀ (21ˀ)mạFalling, glottalized

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Tone Contours Visualization

High  5 ──────────────────●━━━━━━  Sắc (35)
      4 ─────────────────/───────
Mid   3 ────●━━━━━━━━━━━/━━━━━━━━  Ngang (33)
      2 ─────────────────────────
Low   1 ─────────────────────────

High  5 ─────────────────────────
      4 ─────────────────────────
Mid   3 ────●━━━━━━━━━━━━━━━━━━━━
      2 ────────\────────────────  Huyền (21)
Low   1 ─────────●━━━━━━━━━━━━━━━

High  5 ─────────────────────────
      4 ─────────────────────────
Mid   3 ────●━━━━━━━━━━━━━●━━━━━━  Hỏi (313)
      2 ────────\────────/───────
Low   1 ─────────●━━━━━━━━━━━━━━━

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Tone Placement Rules

Diacritics are placed on the main vowel (âm chính) of the syllable.

Single Vowel

Place on that vowelExamples: bá, bà, bả, bã, bạ

Double Vowel + Final

Place on 2nd vowelExamples: hoán, muốn, giác

Double Vowel + No Final

Place on 1st vowel (or vowel with diacritic)Examples: hòa, mưa, sứa

Triple Vowel

Place on middle vowelExamples: tiêu, oai, ươi
Priority rule: If a vowel has a diacritic (ă, â, ê, ô, ơ, ư), the tone mark goes on that vowel.

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Input Methods

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Telex

KeyFunctionResult
aaaâ (circumflex)
eeeê (circumflex)
oooô (circumflex)
whorn/breveơ, ư, ă
dddđ (stroke)
Examples:
  • Vietnam → Vieejt → Việt
  • duoc → duowc → dươc
  • duowcj → được

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VNI

KeyFunctionResult
6circumflexâ, ê, ô
7hornơ, ư
8breveă
9strokeđ
Examples:
  • Vietnam → Vie65t → Việt
  • duoc → du7o7c → dươc
  • du7o7c5 → được

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Phonotactic Constraints

Vietnamese has strict phonotactic rules that determine valid syllable structures.

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No Consonant Clusters

Vietnamese does not allow consonant clusters within a syllable: 
INVALID - English/French-style clusters:
├── *l combinations: bl, cl, fl, gl, pl, sl
│   └── ✗ "black" → must borrow: "blắc" or "bờ-lắc"
├── *r combinations: br, cr, dr, fr, gr, pr, str
│   └── ✗ "press" → must borrow: "prét" or "pờ-rét"
├── s* combinations: sc, sk, sm, sn, sp, st, sw
│   └── ✗ "stop" → must borrow: "xtốp"
└── Final clusters: -nt, -nd, -lt, -lk, -mp, -sk...
    └── Only allowed: -c, -ch, -m, -n, -ng, -nh, -p, -t

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Tone + Final Consonant Restrictions

Rule: Syllables ending in p, t, c, ch can only have sắc or nặng tones: 
┌────────────────────────────────────────────────┐
│         TONE + STOP FINAL CONSTRAINT           │
├────────────────────────────────────────────────┤
│                                                │
│  Final    Valid Tones       Invalid Tones     │
│  ─────    ───────────       ──────────────    │
│  -p       sắc, nặng         ngang, huyền,     │
│  -t       sắc, nặng         hỏi, ngã          │
│  -c       sắc, nặng                           │
│  -ch      sắc, nặng                           │
│                                                │
│  -m, -n   ALL tones         (no restriction)  │
│  -ng, -nh ALL tones         (no restriction)  │
│                                                │
└────────────────────────────────────────────────┘

EXAMPLES:
✓ cấp, cập (sắc, nặng + p)
✓ mát, mạt (sắc, nặng + t)
✗ cảp, cãp, cap, càp (other tones + p)
✗ mảt, mãt, mat, màt (other tones + t)

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Vowel + Final Restrictions

┌─────────────────────────────────────────────────┐
│        VOWEL + FINAL CONSONANT CONSTRAINTS      │
├─────────────────────────────────────────────────┤
│                                                 │
│  Final -ch: only after a, ê, i                 │
│  ├── ✓ ách, êch, ich (sách, bếch, ích)        │
│  └── ✗ ôch, ơch, uch, ưch                      │
│                                                 │
│  Final -nh: only after a, ê, i, y              │
│  ├── ✓ anh, ênh, inh, ynh                     │
│  └── ✗ ônh, ơnh, unh, ưnh                      │
│                                                 │
│  Final -ng: not after e, ê                     │
│  ├── ✓ ang, ăng, âng, ong, ông, ơng, ung, ưng │
│  └── ✗ eng, êng (use -nh instead: anh, ênh)   │
│                                                 │
└─────────────────────────────────────────────────┘
References:
  • Vietnamese Phonology (Wikipedia)
  • Vietnamese Alphabet (Wikipedia)
  • Quốc Ngữ Writing System
  • IPA: International Phonetic Alphabet

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