Information on the Lao language is a bit patchy, especially when you start getting a little deeper and find gaps, inconsistencies, and contradictions in and between sources on the Internet.

Lao vowel sounds are spelled using one or more vowel characters and a couple of characters which are also used for consonants or semivowels. There is a distinction between long vowels and short vowels which plays an important part in determining the tone of a syllable.

Various articles give lists of vowels and diphthongs and tables relating them to their spellings, their length, and their tone. But some words cannot be analysed using just the information in these sources:

ເຂົ້າໜຽວ "sticky rice" /khao niao/

The second syllable appears to contain a triphthong, "ຽວ". Each of the letters "ຽ" and "ວ" can be used either alone or in combination with other letters, but none of the sources I can find mention them in combination with each other.

As vowels "ຽ" usually represents /iːə/ and "ວ" usually represents /uːə/.
As a consonant or semivowel "ວ" usually represents [ʋ] or [w] (depending on dialect).

  1. So what is this "iao" sound in the "niao" of the second syllable? Or should I regard it as two syllables?

  2. How can I reconcile this with Wikipedia's assertion that "Diphthongs are all centering diphthongs with falling sonority"?

  3. Where does the "ao" come from in this combination, is it the same sound that is usually spelled "ເ-ົາ" as seen in the first syllable of the word?

  • 2
    I suggest you look at the Thai language wiki page instead. This sound is called a triphthong there. For determining the tone either analysis is fine, since in each case it’s an open syllable, not a checked one. It’s also clearly one syllable, and –iao does not rhyme with –ao in traditional poetry or generally.
    – neubau
    Jun 9, 2014 at 2:50
  • Interesting. I'm still confused though as this doesn't seem to match with what Yellow Sky says in their answer and comments. \-: Jun 9, 2014 at 5:08
  • 1
    @user2619 - Thai and Lao are related languages, but definitely not the same, they have different phonology, e.g. Thai can have consonant clusters, and Lao cannot. No need to say that aplying data of one language to another languagee is anty-linguistic and leads only to more confusion. Also, the existence of triphthong phonemes in Thai is not a fact agreed upon by everyone, e.g. here they say there're no triphthongs in Thai.
    – Yellow Sky
    Jun 9, 2014 at 10:10
  • 1
    @user2619 - No triphthongs are mentioned in "A Reference Grammar of Thai" by Shōichi Iwasaki & Inkapiromu Puriyā Horie, Cambridge University Press.
    – Yellow Sky
    Jun 9, 2014 at 10:24

1 Answer 1


"ໜຽວ" is 1 syllable, "ຽ" /iːə/ is a typical Lao diphthong with falling sonority, and "ວ" is a consonant /w/, so this is a CVC-type syllable, /n/-/iːə/-/w/, /niːəw/. Note, that /w/ is allowed as the coda in Lao syllables (See A Grammar of Lao, p. 35, section "3.3 Final consonants." Lower on that page there is a list of Lao vowel phonemes and there are no triphthongs there).

Also, /iːə/ is written as "ຽ" only before final consonants, in open syllables /iːə/ is written as ເ◌ຍ, that is another proof that ວ" is onsonant /w/ here. (See this paper, pp. 10-11)

In the first word, the "ເ-ົາ" stands for a combination of a vowel + consonant, /aw/, so the two words have just one thing in common, they both end in /w/. However this /w/ is realised phonetically and acoustically in the coda, it is still the same phoneme as /w/ as the initial consonant. Transliterating this /aw/ as "ao" is just a convention.

  • I think "ວ" was not listed in the tables I found for possible closing consonants. I know it's at the end of some common words though. Let me check ... "Final consonant sounds that are stopped are k (spelled with gaw gai), t (spelled with daw dek), and p (spelled with baw bae)." thailao.net/laochart.htm Jun 7, 2014 at 23:48
  • Actually I've just now found "ຽວ" in one of the charts I'd been using! I'd overlooked it because it uses images for the Lao text so search didn't work! "45. io (long) | Xຽວ ່ກຽວ gio to harvest" thailao.net/laovowel.htm Jun 8, 2014 at 0:01
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    @hippietrail - The "half-open syllables" is a term used in some works on Lao. They're the syllables that end in -w and -j. Their difference from other syllables ending in a consonant is that in the half-open ones the choice of the final consonant is defined by the vowel: after the front vowels /i, iə, e, ɛ/ only the labial /w/ is possible, after the back ones /u, uə, ɯ, ɯə, ɔ/ only /j/ is possible, and after /o, ɤ/ either /w/ or /j/ can be found. See also A Grammar of Lao, p. 35, section "3.3 Final consonants".
    – Yellow Sky
    Jun 9, 2014 at 9:48
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    @hippietrail - I've updated my answer to include what I wrote in the comments.
    – Yellow Sky
    Jun 9, 2014 at 11:02
  • 1
    @hippietrail - That's a trick played by Lao and Thai orthographies, they have symbols for monophthongs, symbols for diphthongs, and symbols for several vowel + consonant combinations, like [am, aw, iːəw], etc. In some books they are also called diphthongs and triphthongs, but they are not, phonologically. Call them "orthographic diphthongs and triphthongs."
    – Yellow Sky
    Jun 13, 2014 at 8:16

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