I couldn't find any etymological information about 奇数{きすう} online. I found it interesting that it has the characters for "strange/odd" and "number", and wondered if it was influenced by English, or if the same meanings arose independently.

  • The Japanese Wikipedia article claims 奇数 is translated from English, but doesn’t provide a source or any further information, so I’m not sure how reliable that is... Commented Sep 29, 2019 at 21:26
  • I would suggest ”kanji” tag since 奇数 should be 奇 + 数. One of the meaning of 「」 is "unbalanced". 偶数 should be 「 」+ 数. One of the meaning of 偶 is "pair". So, the root should come from 漢字 (奇 and 偶) + 数 (numeral). Commented Sep 29, 2019 at 23:36

1 Answer 1


奇数 is an ancient Chinese word, and it is unlikely to be a calque (translation) of the English word odd number. A 2nd century dictionary 説文解字 already has an entry:

奇: 1. strange. 2. not paired.

奇 "odd" and 偶 (耦) "even" are historically mainly technical terms in Chinese cleromancy 易占, but it has a long history of use. But beware that this 奇 sometimes means "lower" numbers (like odd in "30-odd" or "odd pricing") in certain divination procedures.

the Yang lines are odd (or made by one stroke), and the Yin lines are even (or made by two strokes)

乾 "Force" never exceeds 9 and called 奇; 坤 "Field" is a 偶 number, that is not 奇.

日本国語大辞典 dates the first attestation of 奇数 in a Japanese literature in 1477.


But it is, strictly speaking, the "small number" sense in this context, because you can see in the original book...


The next appearance is in 1508, of the right sense.

"隻 is for odd numbers, or Yang numbers"

As it is still before the first contact of Westerners and Japanese, the possibility of being an English (or European) translation is next to zero (I'm saying this because many modern coined Japanese words are seemingly Chinese but are actually calque from Western languages).

As an aside, 奇 has two readings (i.e. stands for two words) in Chinese, although they are etymologically related and indistinguishable in Japanese on'yomi. The "strange" one is (< MC *ɡˠiᴇ < OC *N-k(r)aj) and the "unpaired" one is (< MC *kˠiᴇ < OC *[k](r)aj). So it is technically not true that 奇数 literally means "strange number".

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