Why many words (nouns?) end with つ? Some examples include 寝室{しんしつ}、万年筆{まんねんひつ}. Is there some underlying patterns or rules that Japanese language learners should be aware of?

  • 2
    The words you cite are Sino-Japonic, so (as MickG explains) your question is really, why do so many syllables in Chinese end in /t/?
    – Zhen Lin
    Aug 9, 2014 at 18:00
  • Not really, I am a speaker of Chinese, and 筆's pronunciation in Mandarin does not have an element of つ。
    – user78219
    Aug 9, 2014 at 20:56
  • 10
    Mandarin is not the only Chinese variety, and at any rate I was referring to Middle Chinese. (For a modern variety of Chinese that preserves /t/ in 筆, see Cantonese.)
    – Zhen Lin
    Aug 9, 2014 at 23:07
  • 3
    The other part of this story is the epenthetic /i/ and /u/ in Japanese.
    – user1478
    Aug 10, 2014 at 2:00

1 Answer 1


I can answer for the examples given. We have to go back to their origin as Sino-Japanese terms, and in particular to their Chinese pronunciation. Now I can't actually go back to the Middle Chinese pronunciation the Japanese reading reflects, but Wiktionary may.

In any case, if you take the final characters, you can see on the MDBG Chinese to English Dictionary they are pronounced sat1 and bat1 respectively in Cantonese. The -tsu is the reflex of the final -t of the imported Chinese sound. I think that will cover many of the words you have in mind.

If this does not convince you because of the different vowel, think of going to the Tawan Min Nan Common Usage Words' Dictionary, being careful to look for the Chinese traditional form of the character, as you will not find it if you look for a simplified or Japanese form. There you find the Min Nan pronunciation, which is pit for the second example, so the vowel is fixed. Strangely, the first example turns to sik.

But the Wiktionary comes in there and reconstructs syit for a Middle Chinese pronunciation, with a fanqie (i.e. initial-final-tone explanation) that has 質 as final, read tsit in Min. Now a final -t gets turned into -tsu or -chi (-tu or -ti once, I guess) in Japanese (e.g. nichi/nitsu, 日, presently read nyit in Hakka).

As Wikipedia explains:

fanqie is the explanation of the pronunciation of a character by giving:

  1. A character with the same initial consonant

  2. A character with the rest of the syllable (i.e. all other sounds and the tone) identical

  3. A character marking this is a fanqie.

For example, a modern fanqie for 日 would be 让是切: first character for the r-, second for the -ì, third marking the fanqie style of explanation used.

Expanding any further would have to investigate sound changes in Chinese and Japanese, which I certainly can't do and might bring us off-topic, so I hope this is enough for you. Btw this also answers a question like "why are there many words ending with -pu/-fu/-bu" or "… ending with -ku/-gu", if any such should arise, or at least starts: final stops in Chinese are -t, -p and -k.

  • 4
    It should be pointed out that some changes have happened since Middle Chinese to confuse things: for instance 法 ends in /t/ in Cantonese but originally had /p/; and conversely 立 ends in /p/ in Middle Chinese but ends with つ in Japanese.
    – Zhen Lin
    Aug 9, 2014 at 23:11

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