Ordering of Headwords
 Ordering of Main Headwords
Main headwords are arranged in the order of (1) kana
rendition, (2) absence or presence of inflection, (3) kanji
orthography, and (4) part of speech, and by following the ordering rule specified for each category.
- Ordering by kana rendition
||Entries are arranged in the gojū-on (五十音) order.
In the case of long vowels, the prolonged sound symbol “―” is treated as the same as the vowel preceding it.
||For a given kana, the voiceless sound (清音;seion) precedes the voiced sound (濁音;dakuon), which in turn precedes the semivoiced sound (半濁音;handakuon).
||Syllables represented by small-size kana precede those represented by normal-size kana. In other words, the contracted sound (拗音;yōon) precedes the single-kana sound (直音;chokuon), or the germinated consonant (促音;sokuon) precedes the single-kana sound.
- Ordering based on the absence or presence of inflection
|a)||Non-inflecting words precede inflecting words.
|b)||Kanjigoso precede Sino-Japanese words with identical readings.
|c)||Words written in hiragana precede those written in katakana.
- Ordering by kanji orthography
|a)||Words having their kanji renditions presented in the Kanji Orthography Section precede those without kanji rendition.
|b)||Among words with kanji renditions, those rendered as single-character words precede those rendered as two- or more-character words. The same rule applies to words rendered in two or more characters.
|c)||Words rendered in the same number of kanji characters are arranged in the order of the stroke counts of the initial characters, with lower stroke count taking precedence, and in the order followed by the Kangxi Dictionary (康熙字典) when the initial characters are of the same stroke count. Words sharing the same initial kanji characters are arranged in the order of the stroke counts of the second characters. The same rule applies to arranging words sharing the same initial and second kanji characters, and so on.
- Ordering by part of speech
|a)||When homonymous headwords are arranged on the basis of parts of speech, they are arranged in the following order of precedence:
- Meishi (名詞; Nouns)
- Daimeishi (代名詞; Pronouns)
- Keiyōdōshi (形容動詞; Verbal adjectives)
- Fukushi (副詞; Adverbs)
- Rentaishi (連体詞; Pronoun adjectivals)
- Setsuzokushi (接続詞; Conjunctions)
- Kandōshi (感動詞; Interjections)
- Joshi (助詞; Particles)
- Settōgo (接頭語; Prefixes)
- Setsubigo (接尾語(無活用); Non-inflecting suffixes)
- Zōgoyōso (造語要素; Lexemes)
- Rengo (連語(無活用); Non-inflecting compound words)
- Makurakotoba (枕詞; Pillow words)
- Dōshi (動詞; Verbs)
- Keiyōshi (形容詞; Adjectives)
- Jodōshi (助動詞; Auxiliary verbs)
- Setsubigo (接尾語(活用); Inflecting suffixes)
- Rengo (連語(活用); Inflecting compound words)
|b)||Among nouns, common nouns take precedence over proper nouns.|
- Words of foreign origin of identical kana renditions are arranged in the roman alphabetical order of their original spellings.
 Ordering of Subsidiary Headwords
- Idiomatic phrases, proverbs and the like that begin with the word of a main headword are placed immediately after the main headword.
- When there are two or more subsidiary headwords, they are arranged in the 50(gojū)-on, with subsidiary headwords in kanji arranged in the 50(gojū)-on order of their kana renderings.