nucleus

noun
nu·​cle·​us | \ ˈnü-klē-əs How to pronounce nucleus (audio) , ˈnyü-\
plural nuclei\ ˈnü-​klē-​ˌī How to pronounce nuclei (audio) , ˈnyü-​ \ also nucleuses

Definition of nucleus

1a : the small bright body in the head of a comet
b : the small brighter and denser portion of a galaxy (see galaxy sense 1b)
2 : a central point, group, or mass about which gathering, concentration, or accretion takes place: such as
a : a cellular organelle of eukaryotes that is essential to cell functions (such 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 (see molecule sense 1) 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

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Examples of nucleus in a Sentence

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

Recent Examples on the Web

Police surrounded the plaza at the central post office that has been a nucleus of the revolt. Washington Post, "Algerians protest, celebrate independence day amid tensions," 5 July 2019 For a Grizz team that has spent several years wedded to an aging nucleus and struggling to come up with a coherent vision of the future, the past two drafts—Jaren Jackson Jr. and now Morant and Clarke—have been a great step toward the latter. Andrew Sharp, SI.com, "2019 NBA Draft Winners and Losers: Grizzlies, Suns, and Two Stories for the Pelicans," 21 June 2019 Magic officials regard Isaac and Bamba as the two central pieces to the Magic’s nucleus. Josh Robbins, OrlandoSentinel.com, "Mo Bamba shows flashes of potential in Magic debut," 7 July 2018 But the players’ chemistry peaked late in the season, and, thanks to a nucleus made up of strong veteran leaders and a few young stars, the year ended up being one of Clearview’s best ever. Chris Melchiorre, Philly.com, "Clearview falls short in Group 4 girls' lacrosse state championship," 2 June 2018 Barring trades, the Kings have a first- and second-round draft pick to add to the nucleus. Jason Jones, sacbee, "The Kings now own the NBA's longest playoff drought. So what has them feeling good? | The Sacramento Bee," 12 Apr. 2018 The Phillies haven't had a winning season since 2011, but now have added veteran slugger Carlos Santana, Arrieta and quality relievers to a young nucleus that could show considerable improvement over last season's 66-96 mark. Rob Maaddi, Houston Chronicle, "AP sources: Free agent ace Jake Arrieta, Phillies reach 3-year deal," 11 Mar. 2018 But coach Mike Bibby is gone, and what was left of any nucleus is dispersing. Richard Obert, azcentral, "Salpointe's Evan Nelson gives up MVP trophy to teammate after leading basketball team to PrimeTime title," 15 June 2019 In this scenario, a WIMP would tap an atomic nucleus via the weak force. Quanta Magazine, "Why the Best Place to Find Dark Matter May Be in a Rock," 7 Jan. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'nucleus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of nucleus

1668, in the meaning defined at sense 1a

History and Etymology for nucleus

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

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Statistics for nucleus

Last Updated

13 Jul 2019

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Time Traveler for nucleus

The first known use of nucleus was in 1668

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More Definitions for nucleus

nucleus

noun

English Language Learners Definition of nucleus

biology : the central part of most cells that contains genetic material and is enclosed in a membrane
physics : the central part of an atom that is made up of protons and neutrons
: a central or most important part of something

nucleus

noun
nu·​cle·​us | \ ˈnü-klē-əs How to pronounce nucleus (audio) , ˈnyü-\
plural nuclei\ -​klē-​ˌī \

Kids Definition of nucleus

1 : a usually round part of most cells that is enclosed in a double membrane, controls the activities of the cell, and contains the chromosomes
2 : the central part of an atom that comprises nearly all of the atomic mass and that consists of protons and neutrons
3 : a central point, group, or mass Those players are the nucleus of the team.

nucleus

noun
nu·​cle·​us | \ ˈn(y)ü-klē-əs How to pronounce nucleus (audio) \
plural nuclei\ -​klē-​ˌī How to pronounce nuclei (audio) \ also nucleuses

Medical Definition of nucleus

1 : a cellular organelle of eukaryotes that is essential to cell functions (as reproduction and protein synthesis), is composed of nuclear sap and a nucleoprotein-rich network from which chromosomes and nucleoli arise, and is enclosed in a definite membrane
2 : a mass of gray matter or group of nerve cells in the central nervous system
3 : a characteristic and stable complex of atoms or groups in a molecule especially : ring sense 2 the naphthalene nucleus
4 : the positively charged central portion of an atom that comprises nearly all of the atomic mass and that consists of protons and neutrons except in hydrogen which consists of one proton only

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