核(かく)

かく

noun, prefix

nucleus, core; nuclear

1. nucleus, core, kernel

The central and most important part of something. Used in biology for the cell nucleus, in physics for the atomic nucleus, and figuratively for the core member or central element of a group or organization.

細胞(さいぼう)の核(かく)を観察(かんさつ)する。

To observe the cell nucleus.

彼(かれ)はチームの核(かく)となる選手(せんしゅ)だ。

He is a core player on the team.

この研究(けんきゅう)グループの核(かく)となっているのは、若手(わかて)の研究者(けんきゅうしゃ)たちだ。

It is the young researchers who form the core of this research group.

2. nuclear (as prefix)

Used as a prefix in compound words related to nuclear energy, nuclear weapons, or nuclear science.

核(かく)エネルギーの利用(りよう)。

The use of nuclear energy.

核(かく)実験(じっけん)に反対(はんたい)する。

To oppose nuclear testing.

核(かく)の脅威(きょうい)は冷戦(れいせん)時代(じだい)から続(つづ)いている。

The nuclear threat has continued since the Cold War era.

COMMON COMPOUNDS (sense 2, nuclear):

核兵器(かくへいき): nuclear weapons
核実験(かくじっけん): nuclear test
核融合(かくゆうごう): nuclear fusion
核分裂(かくぶんれつ): nuclear fission
核家族(かくかぞく): nuclear family

COMMON COLLOCATIONS (sense 1, core):

核(かく)となる: to serve as the core
核(かく)を成(な)す: to form the nucleus of
組織(そしき)の核(かく): the core of an organization

Usage

核家族(かくかぞく) (nuclear family) uses 核(かく) in the sense of "core/nucleus" rather than "nuclear weapons," though the English term "nuclear family" has the same etymological origin.

Related Words

Related: 核心(かくしん)

Related: 核兵器(かくへいき)

Compare: コア (core)

general

Added 2026.2.23 20:16 · Revised 2026.9.2 13:01

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