Nucleus (noun) Definition, Meaning & Examples

noun, plural nu·cle·i [noo-klee-ahy, nyoo-], /ˈnu kliˌaɪ, ˈnyu-/, nu·cle·us·es.
  1. a central part about which other parts are grouped or gathered; core: A few faithful friends formed the nucleus of the club.
  2. a specialized, usually spherical mass of protoplasm encased in a double membrane, and found in most living eukaryotic cells, directing their growth, metabolism, and reproduction, and functioning in the transmission of genic characters.
  3. the positively charged mass within an atom, composed of neutrons and protons, and possessing most of the mass but occupying only a small fraction of the volume of the atom.
  4. a mass of nerve cells in the brain or spinal cord in which nerve fibers form connections.
  5. a particle upon which condensation of water vapor occurs to form water drops or ice crystals.
  6. a fundamental arrangement of atoms, as the benzene ring, that may occur in many compounds by substitution of atoms without a change in structure.
  7. the condensed portion of the head of a comet.
  8. Phonetics.
    • the central, most prominent segment in a syllable, consisting of a vowel, diphthong, or vowellike consonant, as the a-sound in cat or the l-sound in bottled; peak.
    • the most prominent syllable in an utterance or stress group; tonic syllable.
noun plural -clei (-klɪˌaɪ) or -cleuses
  1. a central or fundamental part or thing around which others are grouped; core
  2. a centre of growth or development; basis; kernel
  3. (in the cells of eukaryotes) a large compartment, bounded by a double membrane, that contains the chromosomes and associated molecules and controls the characteristics and growth of the cell
  4. any of various groups of nerve cells in the central nervous system
  5. the central portion in the head of a comet, consisting of small solid particles of ice and frozen gases, which vaporize on approaching the sun to form the coma and tail
  6. the positively charged dense region at the centre of an atom, composed of protons and neutrons, about which electrons orbit
  7. a fundamental group of atoms in a molecule serving as the base structure for related compounds and remaining unchanged during most chemical reactions
  8. botany
    • the central point of a starch granule
    • a rare name for nucellus
  9. the most sonorous part of a syllable, usually consisting of a vowel or frictionless continuant
  10. the largest individual that is a mereological part of every member of a given class
Plural nuclei (nōōklē-ī′)
    Nucleus (noun) Definition, Meaning & Examples

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