Which of these words are cognates (share a common etymology)?

  • 住【す】む ("live") (rarely 棲む or 栖む)
  • 澄【す】む ("clear") (rarely 清む)
  • 済【す】む ("end")

According gogen allguide and several dictionaries such as the 大辞泉【だいじせん】, 済む derives from 澄む. Perhaps the English expression I believe that the issue is #cleared up#. helps to illustrate this relationship.

The 広辞苑【こうじえん】 dictionary (6th ed.) speculates that 住む derives from 巣【す】 ("nest"), and lists 巣にいる as the first (ie oldest) meaning. It also quotes the following phrase from the 古今和歌集【こきんわかしゅう】 providing a certain plausibility for the suggested etymology: 花【はな】に鳴【な】く鶯【うぐひす】、水【みづ】に住【す】むかはづの声【こゑ】を聞【き】けば. Although, it is not quite clear to me why 住む here would mean 巣にいる specifically and not to live in general.

This suggest that 住む is unrelated to 澄む・済む. However, I did not find any information regarding the origin of 澄む.

Are the above mentioned sources correct? Is 澄む cognate with 住む, or are they not related at all?

  • 3
    Although 澄む does contain an up (登), my initial intuition is quite the opposite -- all three すむ (住, 澄/清, 済) have down as in settle down (落ちつく) in common. The Chinese character 住 means to stay or to stand (居る, 止まる). Maybe すむ is also related to やむ, やすし (安, 靖) and やすむ. The Kanji 安 and 靖 both have the meaning of to stop/to be stable.
    – Yang Muye
    Commented Oct 28, 2014 at 2:14
  • This sounds like a plausible suggestion to me. Whether or not this is the actual origin of all three words, I could understand how all three meaning are derived meaning are derived from."settle down". I think we can ignore the kanji altogether as this is about native(?) Japanese words.
    – blutorange
    Commented Oct 28, 2014 at 16:38
  • 1
    For what it's worth, 澄 apparently derived from the idea that dirty water, when you let it rest, the clear water will end up at the top, and the dirt will sink down to bottom -- it settles down.
    – blutorange
    Commented Oct 28, 2014 at 16:46

1 Answer 1


Much as described in the question comments by Yang Muye and blutorange, 1) all of these sumu verbs derive from Old Japanese in ways that make the kanji irrelevant to a discussion of etymology, and 2) all of the modern senses of sumu arise from an underlying idea of to settle. Interestingly, the English term to settle covers most of the same meanings as the Japanese sumu: to live in a place, to become clear (such as water), to finish, to be fully paid (such as an account), etc.

(This same etymology was briefly mentioned in this other post.)

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