I am very new to Japanese, but I noticed this today.

In Wiktionary article on 一歩 we see that the pronunciation is いっぽ. In article for 一 we see that there is a nanori reading いっ. On the other hand in the article for 歩 we see that only sensible reading here would be ほ. But put together we get いっぽ. Also in Wikipedia article for っ, it says that sokuon won't appear before h, except in loanwords or nonstandard speech.

So, why there appears to be a っ before h here? And why does it appear to transform the ほ to ぽ?

  • 一 + h- sound often turns into ipp- sound. Other common examples are 一杯、一般. You could even say 一 is irregular in how often it takes sokuon. Could you cite that wikipedia article directly? I couldn't find what you mentioned.
    – HAL
    Commented Jun 19, 2013 at 22:25
  • 1
    一般, 一匹, 一分, 一片, 一方. This phenomenon occurs for the whole ハ行.
    – Earthliŋ
    Commented Jun 19, 2013 at 22:30
  • 2
    For ippo, it isn't considered to be appearing before h. It's considered to be appearing before p.
    – HAL
    Commented Jun 19, 2013 at 22:33
  • 1
    For any counting word beginning with はひふへほ just assume that number 1-3-6-8 are going to be odd. Others can explain why, but rather than wracking your brain a good rule of thumb is 1-6-8 change H -> PP, and 3 changes H -> B.
    – jmac
    Commented Jun 19, 2013 at 22:40
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    While it is true that いっ is listed as a nanori reading that is completely irrelevant. Would it help if I pointed out that the a separate on reading of 一 is いつ?
    – HAL
    Commented Jun 19, 2013 at 22:55

2 Answers 2


It's a simple matter of contraction.

一 is normally pronounced as いち (ichi), and 歩 can indeed be pronounced as ほ (ho).

一 can also be pronounced as いつ, and whenever a kanji ending in ち or つ is followed by は、へ、ひ、ほ or ふ, they contract and turn into っぱ、っぺ、っぴ、っぽ or っぷ.

Some more examples:

八百 = はち + ひゃく → はっぴゃく
失敗 = しつ + はい → しっぱい
一杯 = いつ + はい → いっぱい

And so on, and so forth. The more you get in touch with Japanese, the more natural it will become. Do note that this does not happen when the h is naturally already a b, as e.g. in 発売 (はつばい).

It will also happen when the second kanji starts with either a k or a s sound:

一回 = いつ + かい → いっかい
結婚 = けつ + こん → けっこん
一緒 = いつ + しょ → いっしょ
達成 = たつ + せい → たっせい

To be clear: there are of course exceptions, but these are far fewer than words following this rule.


Anyone care to explain the downvote? I don't mind being wrong, but I'd like to know why.


A more helpful heuristic is to regard ぽ as being the underlying form of 歩, and more generally, /p/ as the underlying form of any on-yomi beginning with /h/; one then adds the rule that /p/ becomes /h/ between vowels (in on-yomi words) and at the beginning of the word. One should also think of 一 as having /it/ as its underlying form, but usually with an /i/ added to fit into Japanese phonology. Thus, 一歩 is secretly */itpo/, which is realised as /ippo/. This also explains, say, 散歩 /sanpo/.

  • This must be limited to 歩 because for other words with the 'h' underlying 'p' like the above-mentioned [一匹]{いっぴき} you end up with [三匹]{さんびき} which just adds confusion (if it's an underlying P that changes to H, where does the B come from?)
    – jmac
    Commented Jun 19, 2013 at 22:37
  • For 三 there is usually a rule that converts /np/ to /nb/ – the technical term is voicing assimilation. But there are exceptions too.
    – Zhen Lin
    Commented Jun 19, 2013 at 22:41
  • @ZhenLin "But there are exceptions too", yes, like 三泊, 三品 etc. If my limited linguistic understanding is correct, that seems to indicate that these combinations are already fossilized or lexicalized or whatever the term is. So that raises the question of whether the import of these classifiers took place at different times, during only some of which the phonological processes were active.
    – dainichi
    Commented Jun 20, 2013 at 3:06
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    Just for reference, there's a little bit of discussion of a similar analysis on p.167 of Shibatani's The Languages of Japan.
    – user1478
    Commented Jun 20, 2013 at 3:14

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