Main Entry:

nu·cle·us

Pronunciation:

\ˈnü-klē-əs, ˈnyü-\

Function:

noun

Inflected Form(s):

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

Etymology:

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

Date:

1704

1 a: the small bright body in the head of a comet b: the small brighter and denser portion of a galaxy2: 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 neutrons3: the peak of sonority in the utterance of a syllable4: a basic or essential part : core <players who are the nucleus of the team>