核

Phono-semantic compound composed of:

木 (mù) — “tree, wood,” indicating relation to plants or fruit.

亥 (hài) — providing sound and suggesting something enclosed or contained.

Originally, the character depicted the woody center or pit of fruit — the solid inner part around which life or growth revolves.

This sense naturally extended to denote the central core of things, whether physical or conceptual.

In modern Chinese and Korean, 核 is heavily used in scientific and technical terms:

Physics: 原子核 (atomic nucleus), 核反應 (nuclear reaction).

Biology: 細胞核 (cell nucleus), 核酸 (nucleic acid).

Politics: 核武器 (nuclear weapons), 核抑止力 (nuclear deterrence).

Its symbolic meaning of “center and power” connects well with the original notion of a “seed” that holds potential and energy.

核心 (핵심) — core, essence, nucleus

原子核 (원자핵) — atomic nucleus

核能 (핵능) — nuclear energy

核武器 (핵무기) — nuclear weapon

核酸 (핵산) — nucleic acid (biology)

核桃 (호도 / 핵도) — walnut (literally “seed peach”)

核查 (핵찰) — verification, inspection

核准 (핵준) — approval, ratification

核對 (핵대) — cross-check, verification

Cultural & linguistic notes:

In classical Chinese, 核 and 覈 were often interchangeable, both carrying senses of “to examine” and “to verify.”

In modern simplified Chinese, 核 officially replaced 覈.

e.g., 核實 (to verify) = 覈實 in traditional form.

In Korean and Japanese, the semantic range narrowed to “core, nucleus, kernel.”

Example idioms & phrases:

核心人物 — “core person” — key figure, central person.

抓住問題的核心 — “grasp the problem’s core” — focus on the essence of the issue.

核爆 — "nuclear explosion" — refers to atomic detonation.

核時代 — "nuclear age" — modern technological era defined by nuclear power.