nucleus

A nucleus is often called the brain, or control center, of a eukaryotic cell (that is, a cell with a nucleus).

The noun nucleus has several senses, though most of them will appear in science. If a biology teacher says nucleus, she is probably talking about a cell (or a group of cells), but a physics teacher would be talking about the center of an atom, or possibly even the center of a comet’s head. Step out of science class, and nucleus likely refers to a core group — like the math fanatics that math club could not function without.

Definitions of nucleus
  1. noun
    a part of the cell containing DNA and RNA and responsible for growth and reproduction
    synonyms: cell nucleus, karyon
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    types:
    pronucleus
    the nucleus of the ovum or sperm after fertilization but before they fuse to form the nucleus of the zygote
    subthalamic nucleus
    an oval mass of grey matter located in the caudal part of the subthalamus; associated with the striate body
    type of:
    cell organ, cell organelle, organelle
    a specialized part of a cell; analogous to an organ
  2. noun
    the positively charged dense center of an atom
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    type of:
    center, centre, midpoint
    a point equidistant from the ends of a line or the extremities of a figure
  3. noun
    a small group of indispensable persons or things
    synonyms: core, core group
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    types:
    cadre
    a nucleus of military personnel capable of expansion
    type of:
    set
    a group of things of the same kind that belong together and are so used
  4. noun
    any histologically identifiable mass of neural cell bodies in the brain or spinal cord
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    types:
    dentate nucleus
    a large laminar nucleus of grey matter within the white matter of each cerebral hemisphere
    type of:
    neural structure
    a structure that is part of the nervous system
  5. noun
    the central structure of the lens that is surrounded by the cortex
    synonyms: lens nucleus
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    type of:
    anatomical structure, bodily structure, body structure, complex body part, structure
    a particular complex anatomical part of a living thing
  6. noun
    (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail
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    type of:
    center, centre, midpoint
    a point equidistant from the ends of a line or the extremities of a figure
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