What is the meaning of 喉音?

glottal/laryngeal consonant

a guttural onset consonant, any of the group of consonants represented by the Middle Chinese pronunciation the following 字母 (zìmǔ): (/ʔ/), (/h/ or /x/), (/ɦ/) and (/j/)

a guttural onset consonant, any of the group of consonants represented by the Middle Chinese pronunciation the following ( (literally mother) means "base sound"; the character before it is the one that bears the onset consonant): 影母 (/ʔ/), 曉母 (/x/), 匣母 (/ɦ/) and 喻母 (/j/)

a guttural sound

Synonym of 声門音 (seimon'on, glottal sound)

Source: wiktionary.org