嗅

By extension: to perceive, to sense intuitively, or to investigate by subtle perception.

In both classical and modern usage, 嗅 primarily denotes the physical act of smelling, but often carries connotations of awareness or discernment beyond mere olfaction.

Ideogrammic compound:

口 (입 구) — representing the mouth, the organ associated with exhalation and inhalation in ancient character logic.

臭 (냄새 취) — meaning “smell,” “odor,” or “stink,” depicting a nose and vapor rising from it.

Together, 口 + 臭 depict the act of breathing in or detecting odor, symbolizing both physical smell and the broader notion of perception through air or breath.

Unlike many other sensory verbs that are phono-semantic compounds, 嗅 is purely ideographic, combining two sense-related elements.

In Shuowen Jiezi (說文解字) no direct entry for 嗅, but instead for 齅, defined as:

「齅，嗅也。从鼻，臭聲。」

“齅 means to smell; composed of 鼻 (nose) with phonetic 臭.”

This confirms that 嗅 is a later simplified or variant form of 齅, retaining the same meaning and closely related semantic structure.

Semantic evolution:

Literal: to smell or inhale an odor.

Extended: to detect, sense, or perceive through instinct.

Figurative: to investigate or “sniff out” secrets, dangers, or opportunities (嗅探).

Scientific/medical: to denote olfactory perception (嗅覺).

嗅覺 (후각) — sense of smell; olfaction

嗅診 (후진) — diagnosis by smell (traditional medicine)

嗅察 (후찰) — to detect by smell; to perceive intuitively

嗅味 (후미) — scent, odor, aroma

嗅探 (후탐) — to sniff out, to investigate secretly

Kangxi Dictionary (康熙字典, vol. 259):

「嗅，《字彙》古作齅。《集韻》許救切，音朽。《說文》無嗅字。」

“嗅 was anciently written as 齅. Pronounced xiù. Not listed as a separate character in Shuowen Jiezi.”

Zhuangzi (莊子 · 齊物論):

「耳目鼻口，心之役也。」

“The ears, eyes, nose, and mouth are the servants of the heart” — Though 嗅 itself is not used here, the 鼻 (nose) embodies the same conceptual domain of sensory perception as 嗅, later appearing in the same semantic field in Han medical texts.

Huangdi Neijing (黃帝內經 · 靈樞):

「鼻者，氣之門也，能嗅香臭。」

“The nose is the gate of qi; it can smell fragrance and stench” — The explicit use of 嗅 in early medical commentaries emphasizes the physiological and energetic role of smell.

Book of Later Han (後漢書 · 方術列傳):

「能嗅藥氣而辨寒熱。」

“He could smell the scent of herbs and discern their warm or cold nature” — Here 嗅 extends to diagnostic intuition through the sense of smell.

In Confucian texts, sensory verbs such as 聽 (to listen), 見 (to see), and 嗅 (to smell) were often used metaphorically for awareness and discernment — implying proper moral perception.

In Daoist and medical philosophy, 嗅 is part of the human-sensory system that mediates qi (氣) exchange between body and environment; the act of smelling signifies connection with life-force.

In Buddhist writings, 嗅 occurs in the list of sensory consciousnesses (六識), specifically as 鼻識 — the consciousness of scent perception, one of the “six faculties of contact” (六觸).

From ancient medical and philosophical texts to modern usage in words like 嗅覺 (“olfaction”) and 嗅探 (“to sniff out”), this character expresses both a bodily function and an intellectual metaphor — the refined human capacity to perceive the invisible essence of things.