This question is based on my somewhat limited understanding and observation of places I have been to so I may be falling victim to a bad sample size. If that is the case, please alert me.

In the couple of years I have now been living in Japan and from the places I have been to, I have noticed that rivers, lakes and mountains often include the kanji 川、湖 or 山 in their names. However, it strikes me as odd that rivers (宇【う】治【じ】川【がわ】、淀川【よどがわ】、鴨川【かもがわ】 and 江【え】戸【ど】川【がわ】) are typically if not exclusively read using the Kun-reading of 川【かわ】, while it seems to me that mountains (比【ひ】叡【えい】山【ざん】、富【ふ】士【じ】山【さん】) and especially lakes (琵【び】琶【わ】湖【こ】、支【し】笏【こつ】湖【こ】) are typically read using the respective kanji’s On-reading. Is this a general rule and if so, why is it so?

For clarity: I am only focussing on the pronunciation of 川、山 and 湖; not any of the other kanji that make up the names I have quoted. There are probably further kanji that serve similar purposes (as in the English-language examples of Currumbin Creek versus Brisbane River) whose kanji I have yet to learn or notice. Feel free to include such ones in your answers.

  • 3
    [浅間山]{あさまやま} [愛宕山]{あたごやま} [稲荷山]{いなりやま} とかもありますけどね‥
    – chocolate
    Jun 9, 2019 at 14:56
  • 1
    My comment may deserve a downvote, but great question and asked in the right forum. Asking this question from 100 randomly picked Japanese people is probably as likely to produce the right answer as asking 100 randomly picked Americans why "he don't" is incorrect, but here someone may actually know. Just speculating, but maybe rivers where "discovered" and named later than lakes and mountains, since while one can see (the entire) mountain and lake, you can only see the very local part of a long winding river) unless you spend extra efforts.
    – Tuomo
    Jun 9, 2019 at 15:02
  • asosan and fujisan use the on reading.
    – Jack Bosma
    Oct 8, 2019 at 17:12

1 Answer 1


The likely reason for these names, at least, is because in this context (actual names of mountains), as part of a toponym, the kanji is being used as a standard suffix for "mountain". This suffix is read さん or ざん (i.e., using the 音読み/on reading, as you stated).

In other instances and contexts, the kanji 山 is read with the kun reading やま, but this is usually in family names (e.g., 山田 Yamada and 山本 Yamamoto) and other compounds. So basically it is pronounced using the on sound when used as a suffix in a place name, similar to how English speakers often use the prefix Mt. for "mountain" when it's placed before the name of a mountain.

Of course there is always someone wiser than the first answerer, so I'm hoping someone else can shed more light on it for you, but if I understand your question, that's the basic answer to my understanding.

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