nucleus

Noun

• the central structure of the lens that is surrounded by the cortex

• any histologically identifiable mass of neural cell bodies in the brain or spinal cord

• (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

• a small group of indispensable persons or things
  • five periodicals make up the core of their publishing program
    

• the positively charged dense center of an atom

• a part of the cell containing DNA and RNA and responsible for growth and reproduction

Related words

• Synonyms: 
  lens nucleus , core , core group , cell nucleus , karyon