I'm interested in why the extra small tsu in included in the word デバッグ but not バグ.

Are there any rules governing voicing in words formed via reduplication?

Lyman's rule may explain this, but does anyone know any more information on why the triple voiced compound is resolved by adding a small tsu (like maybe why a long sound or something different isn't used)

2 Answers 2


I'm fairly certain that this has to do with pitch in Japanese and accentuation in English.

The natural pitch for デバグ【HLL】 is HLL, whereas デバッグ【LHLL】 would naturally be LHL (and バグ【HL】 is HL). To mimic accentuation by pitch (i.e. accented syllables get a high pitch after transliteration), the ッ is necessary to give the バ a (natural) high pitch. バグ already has the right pitch pattern and the best pronunciation approximation to "bug".

(Besides, バッグ is already a word, although here the ッ is probably used to imitate the /æ/ sound, like in キャシュ "cash".)

So both バグ and デバッグ are to be the expected transliterations, and either pair バッグ/デバッグ and バグ/デバグ has shortcomings, albeit being more consistent in some sense.

Update 2022. Darius Jahandarie points out that nowadays katakana loanwords (especially computer/tech-related terms) are increasingly often pronounced with the heiban (平板) pitch accent (see Wikipedia on Japanese pitch accent for a brief description), so that the pitch accents for the two words in question would be バグ【LH】 and デバッグ【LHHH】.

  • 2
    This is probably the correct answer. Japanese loanwords also use long vowels to indicate a downstep in the middle of the long vowel, often to imitate English diphthongs where half of the diphthong is stressed.
    – ithisa
    Nov 19, 2013 at 14:09
  • @user54609 Could you give an example for "Japanese loanwords [that] also use long vowels to indicate a downstep in the middle of the long vowel, often to imitate English diphthongs where half of the diphthong is stressed"?
    – Earthliŋ
    Nov 19, 2013 at 16:15
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    アニメーション /a.ni.meꜜ.e.sjon/
    – ithisa
    Nov 19, 2013 at 20:50
  • 1
    I'v never realized this but now many katakana versions of peoples names make much more sense to me now. Especially if you consider the different transcription versions of the original name in French, German or English for example. Great question and answer Aug 23, 2019 at 9:33
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    For any new viewers of this answer, it's been almost a decade since this answer was posted, so FWIW, due to heibanification of katakana loan words (esp computer or tech related terms), these days バグ is said LH, and デバッグ is fairly often said LHHH. Mar 18, 2022 at 19:42

I do not know for sure but suppose that it is highly related to the original word that was used.

In case of デバッグ this easily may be debugging, not the debug. And then formal transliteration was contracted even shorter. We know many examples like colloquial バイト which is a contraction of アルバイト.

Of course this is only a theory and more detailed answer is highly appreciated.

  • 1
    interesting to note, though, that the wikipedia page for バグ refers to a buggy program as "バギー・プログラム," and I'd assume that it would be transliterated the same way as debugging. I wonder if it's just an irregularity?
    – ssb
    Nov 19, 2013 at 4:23
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    I think most Japanese programmers don't use the phrase "バギー・プログラム".
    – user4688
    Apr 16, 2014 at 9:24

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