噫

Physiological: A belch, heave, or general exhalation; may function as a verb meaning "to breathe out" or "to emit."

Emotional (Interjection): A marker of breathy release used to express lamentation (alas), realization or surprise (ah, oh), or contempt (a dismissive huff).

Primarily occurs as an evocative particle sitting outside the core syntax; it colors the mood of the speaker without altering the grammatical structure of the sentence.

Distinguished from other "mouth" (口) glyphs by the nature of the sound: 嗚 (wū) generally indicates a more audible wail or loud sobbing, and 唉 (ài) typically denotes a specific sigh of resignation or agreement. 噫 is characterized by a breathier, sometimes silent or sharp release of air.

The Tang-period reading (qiə) and Fanqie (於其 烏界) suggest a phonetic evolution distinct from the modern Mandarin reading (yī), confirming its membership in a family of onomatopoeic breath sounds.