Thai Word and Syllable Stress

Stress in Thai is an under-documented aspect of the language. In this article, I will clear up exactly how stress works in Thai, how it interacts with tone, and how you can predict word stress for any Thai word to instantly sound more like a native speaker.

As a new Thai learner, the lack of documentation around word stress surprised me, because after listening to just a few example sentence recordings, it was very apparent to me that certain syllables are significantly more prominent than others, so-called “long” vowels just don’t sound as long as they should in many cases, and tones sound different depending on where they are in the word.

So, without further ado, let’s clear up exactly how this all works.

The 3 levels of syllable stress in Thai words

For starters, it’s important to understand that every syllable in Thai can have one of 3 stress levels: full stress, reduced stress, or no stress (unstressed).1See Peyasantiwong 1986 for a full investigation leading to this conclusion.

This may seem overwhelming, but there’s actually a parallel in English, which has primary stress, secondary stress, and unstressed syllable. Read more about it here. For example, in the word “fantastic”, the first syllable has secondary stress (which is why it’s pronounced with a full /æ/ instead of being reduced to a schwa /ə/), the second syllable has full stress (so it’s a loud and long /æ/), and the last syllable is an unstressed, short /ɪ/ vowel sound.

Bringing this back to Thai, here’s how each vowel in a word is pronounced depending on its stress level:

  1. fully stressed syllables: these are pronounced the way textbooks tell you every Thai syllable is pronounced; long vowels are long, short vowels are short, and the tone is clearly audible.
  2. reduced syllables: these maintain their tone, but vowels are shortened. As Peyasantiwong puts it, “Both long and short vowels are reduced in length; originally long vowels are reduced to approximately the length of short vowels, and originally short vowels are reduced to about half their original length.” For example, /tɛːŋ/ would become [tɛŋ], and /tɛŋ/ would become [tɛ̆ŋ] (extra short).
  3. unstressed syllables: these syllables completely lose their tone, their vowel, and their final glottal stop, becoming just a simple schwa (/ə/) pronounced somewhere in the middle of the vocal range. For example, /taʔ/ would become [tə] (with no specific tone).

Syllable stress assignment

Now that you know the 3 types of syllable stress, the natural question is how to know which syllable has which level of stress in Thai.

The rules are as follows:

  1. The last syllable (or only syllable for monosyllabic words) of every Thai word is always fully stressed (including if it’s a CVʔ syllable)
  2. All non-final syllables are either reduced or completely unstressed.
  3. The only syllables that can be completely unstressed are CVʔ2i.e. a consonant (or cluster), followed by a vowel and a glottal stop. syllables, i.e. syllables that have a short vowel3Short vowels in Thai have an implied glottal stop at the end.
  4. All other syllables (non-final, non-CVʔ syllables) are reduced.
  5. If a word only consists of CVʔ syllables and a final syllable, the CVʔ syllables can either be reduced or completely unstressed, depending on speaker preference and speech rate.

These rules only apply to lexicalized compound words, rather than every instance of two lexemes in a row. Read on to see some examples where these rules apply (and where they don’t).

Words with stress reduction

Here are some examples of some groups of words that these rules apply to:

1. Compound words from independent syllables

In compound words composed of two words that can stand alone as separate words, the first receives reduced stress.

Example: น้ำตา (“tear”), a compound of the words น้ำ (“water”) and ตา (“eye”). Rather than being pronounced [naːm˦˥.taː˧], the first syllable receives reduced stress and the word becomes [nam˦˥.taː˧].

2. Multi-syllable loanwords (each syllable does not have an independent meaning)

Since each individual syllable does not significantly contribute independently to the meaning of the word (as the word was borrowed as whole with multiple syllables), non-final syllables receive reduced (or no) stress.


  • สาบาน (“swear”), originally from Sanskrit, is pronounced closer to [sa˩˩˦.baːn˧], rather than [saː˩˩˦.baːn˧] because the first syllable receives reduced stress.4I’m including this as it’s present as an example in Peyasantiwong 1986, but I can’t yet find any recordings that illustrate this convincingly, so take with a grain of salt.
  • ทะเล (“sea”), originally from Old Khmer, is pronounced [tʰə˧.leː˧] rather than [tʰaʔ˦˥.leː˧], since the first syllable (being a CVʔ syllable) becomes fully unstressed.
  • ชนะ (“to win”), from Old Khmer, is pronounced [t͡ɕʰə˧.naʔ˦˥], instead of [t͡ɕʰaʔ˦˥.naʔ˦˥], with an unstressed first syllable. Note how the second syllable, despite also being a CVʔ, maintains full stress because it’s the last syllable of the word.
  • กะลาสี (“sailor”), originally from Persian, is pronounced [kə˧.la˧.siː˩˩˦], rather than the full [ka˨˩.laː˧.siː˩˩˦]5Speakers will often pronounce the second syllable with full-like stress when speaking slowly or carefully, but when speaking quickly, will reduce it to reduced stress. Though according to Peyasantiwong, such vowels will actually still be pronounced slightly longer than a short vowel. I’ve taken the liberty of simplifying this for the sake of reader digestibility, though., with a fully unstressed first syllable and reduced second syllable.
  • รัฐบาล (“government”), from Pali, is pronounced [răt̚˦˥.tʰə˧.baːn˧], with a reduced first syllable and weak second syllable. This is a great example of the linker syllable phenomenon in Thai, where an extra syllable (in this case /tʰa/) is inserted between two syllables in a loan word that were originally separate words, in this case raṭṭha and pāla, when adapting the word to fit Thai phonology. Such linker syllables are always unstressed.
  • มหึมา (“enormous”), from Sankskrit, is pronounced either [mă˦˥.hɯ̆˨˩.maː˧], with reduced stress on the first two syllables, or (depending on speaker preference and speech rate), can even be fully unstressed and pronounced as [mə˧.hə˧.maː˧].
3. Reduplication of a monosyllabic word for emphasis

This is a common pattern where syllables are repeated for emphasis, and the first syllable receives reduced stress.

Example: ถูกถูก (“cheap” repeated twice for emphasis), is actually pronounced [tʰuk̚˨˩.tʰuːk̚˨˩/], with a short [u] vowel in the first syllable.6Note that this is distinct from a different pattern that strongly intensifies the meaning, where the first syllable is assigned a high tone and does not shorten its vowel.

Words without stress reduction

1. Reduplication of a monosyllabic word, but with different vowels

This is a pattern where syllables are reduplicated for emphasis, but with different vowels (rather than with an identical syllable). In this case, both vowels keep their full stress.

Example: พึมพำ (“to mutter”) is pronounced [pʰɯm˧.pʰam˧], where the first syllable is not reduced or unstressed.

2. Colorful or literary language

In these words, both syllables have equal meaning, and can even be reversed in certain situations like in poetry. This type of independence results in them retaining their full stress.

Example: ยอดเยี่ยม (“excellent”) is pronounced [jɔːt̚˥˩.jia̯m˥˩], with a full [ɔː] in the first syllable.

3. Separable compounds

Unlike fixed compounds like น้ำตา (tear from water+eye), there are words that consist of two syllables, but which aren’t treated as singular words (as the two syllables can be separated by e.g. more details or an adjective).

Example: กาน้ำ (“tea pot”), pronounced [kaː˧.naːm˦˥], with a full first syllable. This can be separated into กาต้มน้ำ (with ต้ม between), demonstrating how this is not the same type of compound that undergoes initial-syllable stress reduction.

Bonus: Distinguishing words and phrases by degree of stress

The phenomenon described in this article also gives rise to an interesting situation, where words like น้ำร้อน can be pronounced like [naːm˦˥.rɔːn˦˥] (both syllables stressed) to mean “the water is hot”, and [nam˦˥.rɔːn˦˥] (first syllable reduced) to mean “hot water”.


In this article, I went over the 3 different syllable stress levels in Thai, as well as how to know which syllable has which stress level. Keeping all this in mind will allow you to speak Thai much more naturally, instead of over-enunciating each syllable (that’s just doing more work to sound less natural, not a good trade-off).

Make sure to also read Thai Tones in Stressed and Unstressed Syllables to understand how tones are pronounced depending on the type of syllable stress.




  1. Peyasantiwong, P., 1986. Stress in Thai. In Papers from a Conference on Thai Studies in Honor of William J. Gedney. Michigan Papers on South and Southeast Asia, Center for South and Southeast Asian Studies, University of Michigan, Ann Arbor (pp. 19-39).
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