source: By BruceBlaus. When using this image in external sources it can be cited as:Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. - Own work, CC BY 3.0

noun (plural nuclei |ˈn(y)o͞oklēˌī| )

the central and most important part of an object, movement, or group, forming the basis for its activity and growth:

〖通例単数形で〗(集団などの)中核, 中心, 中枢(部); (考えなどの)核心(core)

e.g. the nucleus of a film-producing industry.

Physics the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.

〘物理〙 原子核〘原子(atom)の中心で, 中性子(neutron)と陽子(proton)から成る〙

Biology a dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material.

〘生物〙 細胞核〘内部に遺伝子を含む〙

Anatomy a discrete mass of gray matter in the central nervous system.

〘解剖〙 神経核

Astronomy the solid part of the head of a comet.

〘天〙 彗星核

early 18th century: from Latin, literally ‘kernel, inner part’, diminutive of nux, nuc- ‘nut’.