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 Considering the additions of Jerami Grant and Michael Porter Jr. to a nucleus of Jokic, Harris and Jamal Murray, the Nuggets are in an enviable place going forward. Mike Singer, The Denver Post, "NBA GMs tab Nuggets as most “fun” team to watch," 17 Oct. 2019 The team blasted a photon beam into spectrometer, and the beam then passed through a canister of liquid hydrogen and reacted with protons in the nucleus of the canister's hydrogen atoms. David Grossman, Popular Mechanics, "'Car Crash' Experiment Opens Up a New Frontier of Physics," 11 Oct. 2019 That team had a nucleus of superstars that would jell into Super Bowl champions the following year. Larry Stone, The Seattle Times, "Loss to Broncos shows Seahawks fans should brace themselves for a rollercoaster season," 10 Sep. 2018 To actually measure that radius, the researchers fire a laser at a gas of muonic deuterium, causing muons to jump to a higher energy level that does not overlap with the nucleus. Quanta Magazine, "New Measurement Deepens Proton Puzzle," 11 Aug. 2016 Now, genetic engineering is more precise and available than ever before, thanks in large part to a new tool first used to modify eukaryotic cells (complex cells with a nucleus) in 2013: CRISPR-Cas9. Jay Bennett, Smithsonian Magazine, "The Top Ten Scientific Discoveries of the Decade," 6 May 2012 Protons and neutrons make up the atomic nucleus, so the sort of work the EIC would do falls under the rubric of nuclear physics. Adrian Cho, Science | AAAS, "Department of Energy picks New York over Virginia for site of new particle collider," 9 Jan. 2020 Defensively, the Vikings rely on the same nucleus of players that has carried them for much of the past decade. Dave Birkett, Detroit Free Press, "Lions vs. Vikings matchup to watch: Trey Flowers has excelled since last meeting," 7 Dec. 2019 And the particle would also show why the two fundamental forces that shape atomic nuclei follow different rulebooks — which is why physicists devised the axion in the first place, in the 1970s. Quanta Magazine, "Top Dark Matter Candidate Loses Ground to Tiniest Competitor," 27 Nov. 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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Time Traveler for nucleus

Time Traveler

The first known use of nucleus was in 1668

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Statistics for nucleus

Last Updated

23 Feb 2020

Cite this Entry

“Nucleus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nucleus. Accessed 26 Feb. 2020.

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More Definitions for nucleus

nucleus

noun
How to pronounce nucleus (audio)

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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