開かい口こう音おん

noun

open-mouth sound; pronunciation without a medial glide

In Chinese phonology, a syllable that lacks a medial glide (such as -i-, -u-, -ü-) between the initial consonant and the central vowel. Technical term used in historical Chinese phonetics and Sino-Japanese studies.

• 中ちゅう古こ中ちゅう国ごく語ごの開かい口こう音おんは、介かい音おんを持もたない音おん節せつを指さす。

  In Middle Chinese, 開口音 refers to syllables without a medial glide.

noun

long 'o' from 'a' + 'u' combination

In Japanese historical phonology, the long /oː/ vowel that results from the contraction of /a/ and /u/ sounds, such as in the development of certain Sino-Japanese readings. Rare, specialized term.

• 開かい口こう音おんは、日本にほん語ごの音おん韻いん史しで「アウ」から生しょうじた長ちょう音おん「オー」を説せつ明めいするときに使つかわれる。

  開口音 is used in Japanese historical phonology to explain the long 'o' sound that arose from 'a' + 'u'.