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Noun: nucleus (nuclei)  n(y)ook-lee-us
  1. A part of the cell containing DNA and RNA and responsible for growth and reproduction
    - cell nucleus, karyon
     
  2. The positively charged dense centre of an atom
     
  3. A small group of indispensable persons or things
    "five periodicals make up the nucleus of their publishing program";
    - core, core group
     
  4. (astronomy) the centre 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
     
  5. Any histologically identifiable mass of neural cell bodies in the brain or spinal cord
     
  6. The central structure of the lens that is surrounded by the cortex
    - lens nucleus

Derived forms: nuclei

Type of: anatomical structure, bodily structure, body structure, cell organ, cell organelle, center [US], centre [Brit, Cdn], complex body part, midpoint, neural structure, organelle, set, structure

Part of: atom, cell, comet

Encyclopedia: Nucleus