Does anybody know why this decision was made in pinyin, about not writing any hint of the sound /o/ in liu, instead of writing something like liou or liow ?

The first reaction of any newcomer to Chinese, and also, non-Chinese speakers, is to say lee-oo instead of lee-ow.

Edit: some arbitrary decision seems to have been made by choosing you instead of yu, but with other initials, the choice was: liu, niu, jiu, etc. when the phoneme /ou/ in all cases is the same and one could reasonably expect them to be written the same, or at least to be a good reason as to why it isn't the case.

Edit2: Happens something similar to the final -ui which is pronounced -uei

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    Ok the best answer I've read is that choosing liu instead of liou was just to save one letter. And that this couldn't be done with you -> yu (or iu) because there's already a yu syllable and that would be ambiguous.
    – Petruza
    Commented Jun 20, 2014 at 19:27
  • It's basically a history problem, not language problem. I don't even believe there are any text record of such thing. You can see the design result from any copy of 新华字典, but can't find the reason behind this design. 新华字典 Just tell you it's for saving letters, while I highly doubt that. Commented Nov 19, 2018 at 14:56
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    There are other cases where finals are abbreviated differently. I recommend finding a full initial/final table (it fits on one screen) and marking it up with your own observations and pronunciation notes. For example, the final "uei" is never written out, it's "wei" and "dui". Commented Nov 19, 2018 at 17:59
  • There are many such gotchas in Pinyin. Most Chinese believe Pinyin is a 1 letter:1 sound system and tell foreigners learners that. Some foreigners never realize this and just assume they can't pronounce Chinese or nobody understands them when they're pronouncing it properly. You know you have a good Chinese teacher if they start teaching you this right at the beginning because many untrained teachers just assume Pinyin is a no-brainer. This is probably why most Taiwanese don't know Pinyin. Zhuyin Fuhao, in contrast, only has one single gotcha and is 1:1 otherwise. Commented Mar 13, 2019 at 3:26
  • @hippietrail I wonder what the gotcha is in bopomofo. I have never noticed it.
    – joehua
    Commented Jul 12, 2020 at 6:55

7 Answers 7


The same happens with other characters with the same "finals":

就 - Jiù
扭 - Niǔ

From this page of Chinesepod.com:

Mandarin's iu sound can confuse you because what is written is actually an abbreviated form of "iou," a straightforward combination of the vowel sounds i and ou. Thus the iu syllable sounds similar to the "yo" of the English word "yo-yo," with a bit more "oo" sound on the end. It is written as you when it stands alone, and as iu when it is preceded by a consonant (for example, diu, niu, liu).

Emphasis and bold are mine.

Edit: I think that the reason why we have "you" and "liu" is due to some important facts:

Chinese syllables are all made of initials + finals. Unlike other languages, not all sounds in Chinese can be both initials and finals. For example the [s] sound never occurs at the end of a syllable in Chinese, but it does at the beginning, etc.

For this reason, we cannot have a stand-alone final1. Finals that stand by themselves need an initial anyway, and, apart from "iou-you", this happens to other finals as well:

  • iou —> you
  • uen —> wen
  • iao —> yao
  • u —> wu
  • etc...

At this point we could write "liou", but like it has been mentioned, this could have been done for a reason of "economizing/saving space". This doesn't happen symmetrically to all syllables, but considering Pinyin is an "artificial" system for romanizations, many choices could be just arbitrary. In any case, if I find some other claim that explains more in depth, I'll make sure to add it.

1: This is not true for all the finals. Check the link for "finals" to see which ones can stand by themselves, under the column Final-only form.

  • By the way, I forgot to mention that I was mislead too at first eheheh... :D
    – Alenanno
    Commented Jan 19, 2012 at 23:16
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    I don't think it's "certainly related to the phonologic evolution", given that Pinyin was devised in the past century. Most other romanization schemes (e.g., Wade-Giles, Yale, Gwoyeu Romatzyh, etc.) retain the 'o' in the romanization. The answer may simply be for reducing redundancy and increasing conciseness in spelling (i.e., since the -iu sound doesn't exist in Mandarin, it's safe to use it to represent the -iou sound). Other cases where this happens is with -uei -> -ui, -uen -> un, ü -> u after j/q/x, and -uo -> -o after b/p/m/f.
    – Claw
    Commented Jan 20, 2012 at 22:44
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    Ok, I get the impression that it was just letter ecnomization and no other specific reason. About that there can't be a syllable without initial, what about 阿 a? I regard you, wu as simply not having initial, but whatever.
    – Petruza
    Commented Jan 22, 2012 at 18:53
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    @Petruza you asked "Why liu, jiu, niu and not yu instead of you?" but it doesn't seem you got an answer? The most obvious thing to me is that, because there is no "liu" sound, only "liou" sound, it was able to be made into shorthand. However, there are both "you" (like 油, yóu, oil) and "yu" (like 鱼, yú, fish) sounds, so it cannot be shortened down. Now then, if it was able to be shortened down, why did they, then making the lettering inconsistent? That could be another carry-over from the old 注音符号 system, possibly.
    – Ming
    Commented Jun 19, 2014 at 3:14
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    I believe that other Romanization systems were invented to assist foreigners with consistent ways to write each distinct sound whereas Pinyin was invented to supplement Hanzi and eventually replace it for use by native speakers who already knew all the distinct sounds. Everybody knew what sounds do and don't exist in Mandarin so they could economize on number of letters needed per sound. Basically, Pinyin is not for foreign learners, it's for native speakers. You need to learn Pinyin spelling just as you'd learn French spelling. It's consistent but not obvious without an introduction. Commented Mar 13, 2019 at 3:34

As I said in another answer, I think pinyin was actually developed to help Russian speakers learn Mandarin. It may be that "iu" in Russian is pronounced with an added "o" sound. That question has some other answers with interesting information about the development of pinyin.

In spite of its quirks, I've found pinyin a lot easier to use than zhuyin fuhao. It's a phonetic system that uses symbols instead of letters, often called bopomofo.

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    Russian, as far as I know, has two ways to represent "iu": иу and ю. The first has the stress on the "i", the second on the "u". But both are "ee-oo"... I don't remember an "o" sound like the one in "jiu" or "liu" for pinyin. If some russian native speaker passes by, I'd like to have more insight on this. :)
    – Alenanno
    Commented Jan 20, 2012 at 9:46
  • I agree with @Alenanno based on my little knowledge of Russian.
    – Petruza
    Commented Jan 20, 2012 at 21:01
  • I find Zhuyin Fuhao much easier. But I was already used to and already enjoyed learning new writing systems. It's no harder than learning Cyrillic and just as consistent. Most people seem to have an aversion to learning alphabets, even many who want to learn a language. I don't think learning a new symbol is harder than learning a new sports statistic or piece of celebrity trivia (-; Commented Mar 13, 2019 at 3:39
  • Bopomofo doesn't have the "irregularity" of shortening iou to iu, etc.
    – joehua
    Commented Jul 14, 2020 at 0:05

Because pinyin wasn't created by Westerners; it was created by the Chinese government. Also transliteration systems, by nature, aren't perfect analogues to the mother tongue, and you're just setting yourself up for heartbreak if you expect them to be. Relevant: Gwoyeu Romatzyh

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    I don't expect Pinyin to be anything, I just study it. And this doesn't answer my question.
    – Petruza
    Commented Jan 20, 2012 at 21:01
  • Pinyin is not a transliteration in any other language.
    – gb.
    Commented May 19, 2012 at 7:00
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    Petruza, the posters are trying to tell you that pinyin doesn't work perfectly, especially for someone who learned to use the alphabet to pronounce a different language, i.e. English. Even in English a lot of spellings are not purely phonetic, but a lot of it
    – grayQuant
    Commented Oct 9, 2013 at 1:42
  • Petruza, your question is unanswerable, pinyin doesn't work perfectly even for native speakers. For someone who learned the alphabet for a different language i.e. English, pinyin makes even less sense. It's just a guide to pronunciation, but Chinese can't be learned entirely through it.
    – grayQuant
    Commented Oct 9, 2013 at 1:44
  • I know Pinyin is not perfect, if such a concept can be defined in linguistics. It's not a question of perfection or even quality of Pinyin, it's about a double standard for you and liu, for example. Both have the same exact vowel pronunciation in chinese but have different spellings in pinyin. You could argue that they may not have the same exact pronunciation, but the difference in spelling certainly doesn't reflect that, anyway.
    – Petruza
    Commented Jun 20, 2014 at 19:18

There do exist "o" in the vowel "iu", which is originally "iou".

However, for the convenience of daily using, they omitted the "o". (also, uei --> ui)

  • pinyin: -iou --> -iu
  • zhuyin(注音): 一(i)ㄡ(ou)

now we have:

  1. ㄌ(l)ㄧㄡ(iou) or l+iou=liu: 溜流柳六
  2. ㄐ(j)ㄧㄡ(iou) or j+iou=jiu: 糾(no second tone)久就
  3. ㄋ(n)ㄧㄡ(iou) or n+iou=niu: 妞牛紐拗

But for the case the vowel "iou" appears alone, they replace "i" with "y" (insisting every sound should be a consonant + a vowel), which is

  1. 一ㄡ(iou) or y+iou=you: 悠由友又

Here's a good tutorial on pinyin (by Chicago North Chinese School): http://www.svcs-us.org/docs/academics/2012-2013/HanYuPinYin.pdf

It explains almost every detail (but made a few mistakes).

Btw, zhuyin is written in the upside-down form. Except for that, both systems are merely the same.


Because liu is actually pronounced that way in the first tone and second tone. This applies to -ui and -un.

But in the third tone you have a longer syllable where a schwa is inserted so it sounds like -iou, -uei, -uen

Actually the fourth tone is the shortest, but it goes the other way. 对 dui4 actually sounds like due, the diphthong doesn't finish since it's the shortest tone

Spelling them all differently based on tone doesn't make sense. The shorter spelling is more economical.

  • Very interesting! I'll be keeping my ears tuned looking for this ... Commented Mar 13, 2019 at 3:46
  • That's an original answer I hadn't read before, and makes a lot of sense too.
    – Petruza
    Commented Mar 13, 2019 at 11:43

I think, although pinyin is super helpful, it has serious issues inherent in design. There are many confusing elements there, and this disappearing of "o" sound is only one of them. There are other ones, such as "i" pronounced so differently in "qi, ci, chi", and how come "an" sounds so different in "wan" and "yan", etc.

Pinyin and Mandarin pronunciation are two different things. Pinyin must be bent and manipulated numerous times to be able to fit to natural speech pattern, which exited long before the invention of pinyin.

If interested, read more here: The gulf between pinyin and Mandarin Chinese pronunciation https://mslmaster.com/index.php/teaching-learning-resources/10-resources/54-the-gulf-between-pinyin-and-mandarin-chinese-pronunciation


In addition, if you write jiou it will be ji'ou(奇偶) rather than 就(jiu) and *iu disambiguates that.

  • Yeah, it does serve that purpose too, maybe accidentally, but your answer, as well as many other romanizations (e.g. Japan's Romaji) do handle that ambiguity better IMO, with the apostrophe.
    – Petruza
    Commented Apr 22, 2019 at 15:00

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