Definition of nucleus in English:

nucleus

Syllabification: nu·cle·us
Pronunciation: /ˈn(y)o͞oklēəs
 
/

noun (plural nuclei /-klēˌī/)

  • 1The central and most important part of an object, movement, or group, forming the basis for its activity and growth: the nucleus of a film-producing industry
    More example sentences
    • If this proposal is accepted, the government together with the St Lucian organizations could have an extension of the mission in Brooklyn and an important nucleus for the St Lucian community.
    • The nucleus of the global movement against injustice will not - cannot, should not - be found in the centers of global privilege.
    • And at the moment there is not even the nucleus of a movement to achieve that.
    Synonyms
    core, center, central part, heart, nub, hub, middle, eye, focus, focal point, pivot, crux
  • 1.1 Physics The positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.
    More example sentences
    • The harmless radio waves excite protons that form the nuclei of hydrogen atoms in the body.
    • Electrons produce a small magnetic field as they spin and orbit the nucleus of an atom.
    • Electrons are found in clouds that surround the nucleus of an atom.
  • 1.2 Biology A dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material.
    More example sentences
    • Dense granules surrounding the nucleus are probably cytoplasmic organelles.
    • The cells had round or oval vesicular nuclei with multiple prominent nucleoli.
    • The cells were characterized by large vesicular nuclei with single large nucleoli.
  • 1.3 Astronomy The solid part of the head of a comet.
    More example sentences
    • Sometimes, the stresses are strong enough to break off chunks of the comet's nucleus.
    • The spacecraft will orbit the comet's nucleus.
    • The spacecraft's point of view now captures the shadowed side of the comet's nucleus.
  • 1.4 Anatomy A discrete mass of gray matter in the central nervous system.
    More example sentences
    • Axons travel from the neurons located in nuclei within the brain stem via the cranial nerves without synaptic interruption to the motor end plates on the striated muscle.
    • These effects are produced by fibres projecting from the hypothalamus to parasympathetic nuclei in the brain stem, and to sympathetic centres in the spinal cord.
    • The trochlear nerve nuclei are located ventral to the mesencephalic aqueduct.

Origin

early 18th century: from Latin, literally 'kernel, inner part', diminutive of nux, nuc- 'nut'.

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