nucleus
noun
nu·cle·us
ˈnü-klē-əs 
ˈnyü-
plural nuclei
ˈnü-klē-ˌī
ˈnyü-
also nucleuses
1
a
: 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)
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 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
Re-signing Bichette, who's eligible for free agency at the end of this season, would give Toronto a nucleus to build around for years.
—
Gordon G. Chang, MSNBC Newsweek, 8 Apr. 2025
The next step was to transfer a nucleus with the edited DNA into a dunnart ovum.
—D. T. Max, New Yorker, 7 Apr. 2025
South Carolina will be back too with a young nucleus led by Edwards and MiLaysia Fulwiley.
—Doug Feinberg, Chicago Tribune, 7 Apr. 2025
Previously, research has suggested the formation of the heaviest elements, such as gold, requires copious amounts of neutrons that atomic nuclei can absorb to become larger and larger.
—Charles Q. Choi, Space.com, 7 Apr. 2025
See All Example Sentences for nucleus
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Gordon G. Chang, MSNBC Newsweek, 8 Apr. 2025
The next step was to transfer a nucleus with the edited DNA into a dunnart ovum.
—D. T. Max, New Yorker, 7 Apr. 2025
South Carolina will be back too with a young nucleus led by Edwards and MiLaysia Fulwiley.
—Doug Feinberg, Chicago Tribune, 7 Apr. 2025
Previously, research has suggested the formation of the heaviest elements, such as gold, requires copious amounts of neutrons that atomic nuclei can absorb to become larger and larger.
—Charles Q. Choi, Space.com, 7 Apr. 2025
See All Example Sentences for nucleus
Cite this Entry
“Nucleus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nucleus. Accessed 13 Apr. 2025.
Copy CitationKids Definition
nucleus
noun
nu·cle·us
ˈn(y)ü-klē-əs
plural nuclei
-klē-ˌī
also nucleuses
also nucleuses
: a central point, group, or mass of something: as
a
: the small, brighter, and denser part of a galaxy or of the head of a comet
b
: a cell part that is characteristic of all living things with the exception of viruses, bacteria, and blue-green algae, that is necessary for heredity and for making proteins, that contains the chromosomes, and that is enclosed in a nuclear membrane
c
: a mass of gray matter or group of neurons in the central nervous system
d
: the central part of an atom that includes nearly all of the atomic mass and consists of protons and usually neutrons
Etymology
from modern Latin nucleus "the central part of something," from Latin nucleus "kernel," derived from nux "nut"
Medical Definition
nucleus
noun
nu·cle·us
ˈn(y)ü-klē-əs
plural nuclei
-klē-ˌī
also nucleuses
also nucleuses
1
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
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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