Definition of nucleus
nucleiplay \ˈnü-klē-ˌī, ˈnyü-\ also
1a : the small bright body in the head of a cometb : the small brighter and denser portion of a galaxy (see galaxy 1b)
2 : a central point, group, or mass about which gathering, concentration, or accretion takes place: such asa : 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 illustrationb : a mass of gray matter or group of cell bodies of neurons in the central nervous systemc : a characteristic and stable complex of atoms or groups in a molecule (see molecule 1); especially : ring the naphthalene nucleusd : 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 of nucleus from the Web
Moran's long-running Bandwagon served as its nucleus, drummer Nasheet Waits' multilayered rhythms and Tarus Mateen's earthy electric bass lines consistently driving the music forward.
The waves shrank and expanded space on Earth by just a fraction of the width of a proton, one of the particles that makes up an atomic nucleus.
The change is incredibly small, about one thousandths of the width of a proton, the particle inside the nucleus of an atom.
Allman was the lead singer and keyboardist of the group, and was the nucleus of the band along with his older brother, guitarist Duane Allman, who died in 1971.
In the standard model — the theoretical picture of what physicists think matter is made of — atomic nuclei are broken down into protons and neutrons, which are broken down further into fundamental particles called quarks and gluons.
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.
NUCLEUS Defined for English Language Learners
Definition of nucleus for English Language Learners
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 Defined for Kids
Definition of nucleus for Students
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.
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 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
Seen and Heard
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