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 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>