甲乙

/kapʉ otʉ/ → /kaɸuot͡su/ → /kauot͡su/ → /kɔːot͡su/ → /koːot͡su/

Compound of 甲 (kō, “first”) +‎ 乙 (otsu, “second”), with the orderings based on the ancient Chinese Heavenly Stems.[1][2]

First cited with this reading to a portion of the 続日本紀 (Shoku Nihongi) that was completed in 757 CE.[1]

• (Tokyo) こ​ーおつ [kóꜜòòtsù] (Atamadaka – [1])[2]
• IPA^(key): [ko̞ːo̞t͡sɨᵝ]

甲(こう)乙(おつ) • (kōotsu) ^{←かふおつ (kafuotu)?}

1. [from 1387] the first and second; grade A and B
2. [from 1012] the first two of the Heavenly Stems, 甲 (kinoe) and 乙 (kinoto)
3. [from 1167] the pros and cons of something, the ups and downs, the strengths and weaknesses
4. [from 833] used when talking about any two unspecified things: A and B

甲(こう)乙(おつ) • (Kōotsu) ^{←かふおつ (kafuotu)?}

1. [from 757] (rare) short for 甲乙経 (Kōotsu Kyō), a medical text from the Jin dynasty of ancient China

Shift in reading of kōotsu, using the 慣用音 (kan'yōon, “customary reading”) of kan for the 甲 character.

First cited with this reading in a text from roughly 1423.[1]

• (Tokyo) かんおつ [kàń'ótsú] (Heiban – [0])[2]
• (Tokyo) か​んおつ [káꜜǹ'òtsù] (Atamadaka – [1])[2]
• IPA^(key): [kã̠ɰ̃o̞t͡sɨᵝ]

甲(かん)乙(おつ) • (kan'otsu) 

1. [from circa 1423] (traditional Japanese music) the high notes and low notes, the highs and lows of a piece of music

   Synonym: かりめり (karimeri)

(The following entry is uncreated: かりめり.)