Jukujikun and Ateji Explained

What jukujikun are

Most kanji words can be read one character at a time. 大学 is だい plus がく, and 手紙 is て plus がみ. Jukujikun break that pattern. The name means a native reading (訓) given to a compound (熟字), and the reading only works for the word as a whole.

Take 今日 (きょう, today). 今 is read コン or いま, and 日 is read ニチ, ジツ, ひ or か. None of these add up to きょう. The Japanese word きょう existed first, and the kanji for now and day were attached to it because they match its meaning. 大人 (おとな, adult) works the same way: 大 means big and 人 means person, but おとな is not built from their readings.

Because of this, jukujikun fall outside the usual split between Chinese-derived and native readings described in onyomi vs kunyomi. They are kunyomi in spirit, since the word is native Japanese, but the reading cannot be divided among the kanji.

Common jukujikun to learn first

Japan's official list of everyday kanji, the 常用漢字表 issued in 2010, ends with an appendix (付表) of words with these special readings. It contains 116 words, and many of them appear in beginner Japanese. Here are some of the most useful, all taken from that appendix:

Others in the appendix worth knowing early include 友達 (ともだち, friend), 真面目 (まじめ, serious), 土産 (みやげ, souvenir), 風邪 (かぜ, a cold), 梅雨 (つゆ, rainy season), 七夕 (たなばた, the Star Festival) and 二十歳 (はたち, 20 years old). The day readings are covered in more depth in Japanese dates, and ひとり and ふたり in Japanese counters.

One spelling, more than one reading

A jukujikun spelling can also have an ordinary reading, and the two may differ in meaning or tone. This is where learners get caught out:

• 明日 is あした in everyday speech, あす in more polite or written Japanese, and みょうにち in formal settings. All three mean tomorrow.
• 今日 is usually きょう, but read こんにち it means nowadays, as in 今日的 (こんにちてき, modern). The greeting こんにちは comes from this reading.
• 一日 is ついたち when it means the 1st of the month and いちにち when it means one day or all day.
• 上手 is じょうず (skilled), but in other contexts it is read うわて (upper hand) or かみて (stage left, as seen from the audience).

Context almost always decides. A calendar date with 一日 is ついたち, while 一日中 (いちにちじゅう, all day long) is いちにち. When in doubt, check a dictionary entry for the whole word rather than for each kanji.

What ateji are

Ateji (当て字) means assigned characters. Where jukujikun pick kanji for their meaning, ateji typically pick kanji for their sound, with little regard for what the characters mean. Before katakana became the normal way to write foreign words, many loanwords were spelled this way:

• 倶楽部 (クラブ, club): the sounds く, ら and ぶ, with characters that also hint at enjoyment and a group.
• 合羽 (かっぱ, raincoat): from the Portuguese word capa.
• 珈琲 (コーヒー, coffee) and 瓦斯 (ガス, gas): still seen on cafe signs and in company names.
• 亜米利加 (アメリカ, America): now written in katakana, but its second character survives in 米国 (べいこく, the United States).
• 天麩羅 (てんぷら, tempura): kanji chosen to spell out the sounds of the word.

Some ateji use kanji whose meaning has nothing to do with the word. 寿司 (すし) is the best known example: its characters suggest long life and administering, not food. The spelling is still standard on menus and shop signs.

Jukujikun vs ateji

The two ideas overlap, and some writers describe jukujikun as a kind of ateji. A simple way to keep them apart:

• Jukujikun: the kanji match the meaning, and the reading belongs to the whole word. 今日, 大人, 時計.
• Ateji: the kanji are chosen mainly for their sound, or used regardless of meaning. 倶楽部, 珈琲, 寿司.
• Gikun (義訓): creative one-off spellings by meaning, common in song lyrics and manga, almost always shown with furigana. Many jukujikun began this way before the spelling became fixed.

In daily reading you will meet jukujikun far more often. Ateji for loanwords have largely been replaced by katakana, though they remain on traditional shop signs, menus and in historical terms.

How to learn special readings

1. Learn them as vocabulary, not as kanji readings. Do not file きょう under 今 or 日. Learn 今日 = きょう as one word, the same way okurigana are best learned with their word.
2. Start with time and people words. 今日, 昨日, 明日, 今年, 一人, 二人 and 大人 appear in almost every beginner textbook, so they repay the effort first.
3. Notice the spelling when you type. A Japanese keyboard converts きょう to 今日 and めがね to 眼鏡, which reinforces the link between the whole word and its spelling.
4. Watch for whole-word furigana. In books for learners, the reading of a jukujikun sits over the whole word instead of being split per kanji, which is a quick visual clue.
5. Review them on a schedule. Special readings are easy to mix up with regular ones, so add them to a spaced repetition deck. Apps such as Moji, which shows example words on each kanji, or Anki will bring them back before you forget.

Jukujikun look like exceptions at first, but there are only about a hundred common ones, and many are words you would learn early anyway. Once you expect them, a word like 今日 stops being a puzzle and becomes simply きょう.