nucleus

nu·cle·us

noun \ˈnü-klē-əs, ˈnyü-\

plural nu·clei\-klē-ˌī\ also nu·cle·us·es

Definition of NUCLEUS

1

a : the small bright body in the head of a comet b : the small brighter and denser portion of a galaxy

2

: a central point, group, or mass about which gathering, concentration, or accretion takes place: as a : a cellular organelle of eukaryotes that is essential to cell functions (as reproduction and protein synthesis), is composed of nucleoplasm and a nucleoprotein-rich network from which chromosomes and nucleoli arise, and is enclosed in a definite membrane — see cell illustration b : a mass of gray matter or group of cell bodies of neurons in the central nervous system c : a characteristic and stable complex of atoms or groups in a molecule; especially : ring <the naphthalene nucleus> d : the positively charged central portion of an atom that comprises nearly all of the atomic mass and that consists of protons and usually neutrons

3

: the peak of sonority in the utterance of a syllable

4

: a basic or essential part : core <players who are the nucleus of the team>

Examples of NUCLEUS

1. <a college campus that was a nucleus of opposition to the war>
2. <the nucleus of the movement's methodology has always been passive resistance>

Origin of NUCLEUS

New Latin, from Latin, kernel, from nuc-, nux nut — more at nut

First Known Use: 1704

Related to NUCLEUS

Synonyms: axis, base, capital, central, core, cynosure, epicenter, eye, focus, ground zero, heart, hub, locus, mecca, navel, nerve center, nexus, center, omphalos, seat

Related Words: headquarters; happy hunting ground, hive, hotbed, hot spot, playground, playland; kernel, nub, pith; deep, thick; essence, quintessence, soul; attraction, lodestone (also loadstone), magnet, polestar

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Other Cell Biology Terms

cytology, gamete, vacuole, zygote