Tuesday, December 19, 2017

Why Gakkou Not Gakukou? - Sokuonbin 促音便

Perhaps the word thing you can come across learning kanji is that "school" is gakkou 学校, "student" is gakusei 学生, and "high-school" is koukou 高校. At first glance, there's nothing wrong with this. Until you notice the reading of the kanji varies.

After all, why is gakkou not gakukou? Why is ippatsu 一発 not ichihatsu? Why is ikkagetsu一ヶ月 not ichikagetsu? Why is kekkou 結構 not ketsukou? Why is masshiro 真っ白 not mashiro? Why is mikka 三日 not mitsuka? Why is otte 追っ手 not ote? Why is nikki 日記 not niki? What's up all these words?!

Examples of sokuonbin 促音便, gakukou becoming gakkou 学校, hitsusatsu becoming hissatsu 必殺, nichiki becoming nikki 日記, ichihatsu becoming ippatsu 一発 and totsuha becoming toppa 突破.

Sokuonbin 促音便

The answer is a feature of the Japanese language called sokuon-bin 促音便, a type of "euphonic change," onbin 音便, using the sokuon 促音, which is a geminate consonant sound. This is expressed in Japanese by the small tsu and in romaji by doubling the consonant.
  • gakkouこう

Why It Happens?

Basically, it's because of how the words are pronounced.

When you have a word like gakkou 学校, it's easier to pronounce it as gakkou than it is to pronounce it as gakukou. The tongue slips. People have been saying it that way for so long it's become official.

This is similar to how rendaku 連濁 makes a shini kami 死神 become shinigami 死神.

Besides, it also sounds better. I mean, totsuha 突破 sounds like someone's name, it doesn't ring as nice as toPPA!!! 突破!!!

When It Happens?

The sokuonbin happens in essentially three different cases.

Joint of Hard Syllables

When you have two morphemes (like two kanji, but not always), and they're joined in one word, and the last syllable of the first morpheme and the first syllable of the second morpheme have hard, dry sounds, they end up becoming a sokuon instead.

For example, if the first morpheme ends in chi, tsu or ku, and the second morpheme starts with h, k or t, then it probably becomes a sokuonbin.

Also, chi and tsu also create sokuon sometimes when they come before s or h. And when h is preceded by the sokuon, a handakuten is added and it becomes p instead. (example: ho ほ becomes po ぽ)

Forced Word Boundary

When you have a morpheme which starts with one of the hard syllables above, like k, h, t or s, for example, and you use it as a suffix in a word, it's often the case you add the sokuon in order to let it show it's a separate morpheme in the pronunciation.


For example, the Japanese anime community has the custom of adding the suffix ko 子, "child," written with the kanji for musume 娘, "girl," to random words. When this happens, the suffix usually becomes kko っ娘.

So a girl which uses the pronoun boku gets called a bokukko 僕っ娘, because a bokuko 僕娘 sounds like it's a single word that mixes both things meanings somehow, when it's the one words with one suffix.

You can also see this in the suffix ppoi っぽい. If you said just poi ぽい it'd sound like it's a single adjective. For example: nekopoi ねこぽい looks like one single word, it has less syllables than atatakai 暖かい, "warm," which is a simple adjective.

So, instead, an emphasis is put on the pronunciation of the boundary, nekoppoi 猫っぽい, "cat-like," so the listener or reader can perceive it's separate things.


This can also happen with prefixes, which is why ma 真 and shiro 白 become masshiro 真っ白.

Historic Changes

A last case is when a word's pronunciation simply changed through the years, and by years I mean decades or centuries, or who knows how long.

Such changes are difficult for someone like me to figure out, but I can at least tell you they exist.

For example, shippo 尻尾, "tail," is read as shippo in modern Japanese, but its parts are shiri 尻 and o 尾 respectively. You can tell that o 尾 was treated as if it was a ho and turned into a po. In the past, the word was read shirio 尻尾.


Most te forms of verbs, like totte 取って, actually come from literally connecting the verb to the te. This happens by using the "conjunctive form," the renk'youkei 連用形.

For example, connect toru 取る, "to take," to another verb would look like this: torikaesu 取り返す, "to take back." So when it's connected to the te, it should look like torite 取りて. However, after centuries of languagery, it's become totte 取って instead because of the pronunciation.

(in a similar but different process, yomite 読みて became yonde 読んで)

Join of Vowel

The use of sokuon also happens sometimes when the second morpheme is a vowel and the first is a hard syllable. When this happens, the vowel ends up being treated like a h syllable and turns into p.

For example, shiri 尻 and o 尾 become shippo 尻尾, "tail."

Unwritten Secret

It's important to note that the sokuonbin is a phonetic feature of the Japanese language. It's how people pronounce words. It has nothing to do with writing. The official orthography merely reflects the way people say something in general, but it's not perfect.

That is to say that, in some cases, a word that that's spelled out without sokuonbin is normally pronounced in real life with the sokuonbin.

For example, the word sentaku-ki 洗濯機, "washing machine," is the combination of sentaku 洗濯, "washing [clothes]," and the suffix ki 機, meaning "machine." Most dictionaries will show the word's read sentakuki せんたくき, but people may pronounce it sentakki せんたっき instead.

How Their Spelled?

If you look for it on the internet, you can even find some posts by natives unsure of how to spell out a word with hiragana because they're used to pronouncing it with sokuon. (proof: 洗濯機は「せんたっき」ですか?「せんたくき」ですか?)


For reference, a couple of examples of sokuonbin, specially the first case, which gives the most trouble since it looks like reading of the kanji varies.


After K-syllable.

  • saku 作 + ka
    sakka 作家
  • gaku 楽 + ki
    gakki 楽器
    Musical instrument.
  • toku 特 + kun
    tokkun 特訓
    Special training.
  • toku 特 + ken
    tokken 特権
    Special right. Privilege.
  • kaku 格 + kou
    kakkou 格好
    Appearance. Look. Situation.

After Tsu

  • ketsu 結 + ka
  • hitsu 筆 + ki
    hikki 筆記
    Writing down. Taking notes.
  • hatsu 発 + kutsu
    hakkutsu 発掘
  • shitsu 湿 + ke
    shikke 湿気
  • ketsu 結 + kon
    kekkon 結婚

After Chi

  • ichi 一 + ka
    ikka 一家
    One house. One family.
  • nichi 日 + ki
    nikki 日記
  • ichi 一 + ku
    ikku 一句
    One verse. One poem.
  • ichi 一 + ken
    ikken 一件
    One case. One matter.
  • ichi 一 + ko
    ikko 一個
    One object. One thing. One article.


Note: chi and ti are different romaji of the same syllable, ち, so chi is a T-syllable..

After Tsu

  • metsu 滅 + ta
    metta ni nai 滅多にない
    Rare. (rarely happens)
  • setsu 設 + chi
    secchi 設置
    Establishment. Installation.
  • setsu 摂 + tsu
    settsu 摂津
    (a province of Japan, because there weren't any other words for the tsu + tsu spot)
  • katsu 勝 + te
    katteni 勝手に
    Arbitrarily. On its own.
  • shitsu 嫉 + to
    shitto 嫉妬

After Chi

  • ichi 一 + tai
    ittai 一体
    One body.
    Also: "WTF?"
  • ichi 一 + chi
    icchi 一致
  • ichi 一 + tsu
    ittsu 一通
    One copy of a document.
    A pure straight in Mahjong, tiles 1 to 9!
  • ichi 一 + te
    itte 一手
    One move (in a game).
  • ichi 一 + tou
    ittou 一等


Note: fu and hu are different romaji of the same syllable: ふ, so fu is an H-syllable.

After Tsu

  • shitsu 失 + hai
    shippai 失敗
  • gatsu 月 + hi
    seinengappi 生年月日
    Birth date.
  • shitsu 疾 + fuu
    shippuu 疾風
    Gale. Strong wind.
  • gatsu 合 + hei
    gappei 合併
  • tetsu 鉄 + hou
    teppou 鉄砲

After Chi

  • ichi 一 + han
    ippan 一般
    General. Ordinary.
  • ichi 一 + hiki
    ippiki 一匹
    One small animal.
  • ichi 一 + fu
    ipputasai 一夫多妻
    Polygamy. (literally "one husband, multiple wives.")
  • ichi 一 + hen
    ippen 一変
    Complete change.
  • ichi 一 + ho
    ippo 一歩


After Tsu

  • hitsu 必 + satsu
    hissatsu waza 必殺技
    SURE-KILL TECHNIQUE!!!!!!1111111
  • zatsu 雑 + shi
    zasshi 雑誌
  • tatsu 達 + suru する
    tassuru 達する
    To reach. To arrive at.
  • tatsu 達 + sei
    tassei 達成
  • hatsu 発 + sou
    hassou 発想
    Idea imagined.

After Chi

  • ichi 一 + sai
    issai 一才
    One year old
  • ichi 一 + shitsu
    isshitsu 一室.
    One room.
  • nichi 日 + suu
    nissuu 日数
    A number of days.
  • ichi 一 + seki
    issekinichou 一石二鳥
    Killing two birds with one stone.
    (literally: "one stone, two birds.")
  • ichi 一 + sou
    issou 一層
    One layer. One storey.
    Much more (like, a whole storey more).

Bonus: nichi 日 plus san 産 equals nissan 日産, the car company!

1 comment:

  1. This is a sweet breakdown, thanks! It's totally not one of the more glorious subjects to cover, but I love how comprehensive you made it


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