Shogakukan Unabridged Dictionary of the Japanese Language
Historical Kana Orthography
- In cases where the historical kana orthography differs from the orthography of the headword, the historical orthography is given in square brackets [ ] immediately after the headword.
- The symbols －, •, and are omitted in the entry headings in historical kana forms.
- In case a heading is divided by a hyphen “-“, the portions preceding and following the hyphen are considered separately, and the portion of the compound form whose historical kana orthography coincides with its modern orthography is omitted and replaced by the symbol “:”.
- Indigenous Japanese words are given in hiragana, and Sino-Japanese words in katakana. However, in certain ambiguous cases where a word is customarily associated with a certain kanji form, the historical kana orthography may be used as the basis for a decision.
- For Sino-Japanese words which have undergone pronunciation changes over time such as 観音 (kuwan-on → kuwannon → kannon), 天皇（tenwau → tennō）, and 学校(gakukau → gakkō), their respective original forms are given as their historical kana forms for convenience’s sake.
- Historical kana orthography notes are omitted for some dialectal variants, proper nouns, etc.