樞

Phono-semantic compound:

木 (나무 목) — semantic component, indicates wood or wooden structures (such as doors or frames).

區 (구분할 구) — phonetic component, provides the sound shū / chu and suggests separation, division, or centrality.

Thus 木 + 區 → 樞 — “a wooden structure that turns,” i.e., a hinge or pivot.

In Shuowen Jiezi (說文解字):

「樞，戶樞也。从木，區聲。」

“樞 means the hinge of a door; composed of 木 and phonetic 區.”

The character therefore symbolizes the axis upon which a system revolves, whether physically (door hinge) or conceptually (the central principle of governance, thought, or life).

樞機 (추기) — hinge; pivotal mechanism; central organ (as in 樞機主敎 “cardinal” in Catholic usage)

中樞 (중추) — center; nucleus; nerve center

樞軸 (추축) — pivot; axis; strategic key point

樞要 (추요) — essential; important; vital

樞府 (추부) — central administrative office (historical term)

Kangxi Dictionary (康熙字典, vol. 601):

「樞，戶樞也，引申為機要之處。」

“樞 means a door hinge, and by extension, any place or position of vital importance.”

In literature and philosophy, 樞 signifies the point of balance and control — the unseen center that allows the world, a state, or a person to move in harmony.

Zhuangzi (莊子 · 天道):

「道之樞，虛無之始也。」

“The pivot of the Dao is the beginning of emptiness” — 樞 here denotes the central axis of cosmic transformation.

Book of Han (漢書 · 百官志):

「設中樞府，以總機要。」

“The Central Pivot Office was established to oversee critical affairs.” — an early bureaucratic usage.

The derivative concept 中樞 (중추) came to represent the “nerve center” of both government and the human body — the seat of control and coordination.

Phonetic note: while the standard Sino-Korean reading is 추, some ancient rime dictionaries record a secondary pronunciation 우 (烏侯切), reflecting regional or archaic phonetic variants.