nucleus

noun

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

   noun.body

   Synonyms cell nucleus karyon

   Source: WordNet 3.0

2. the positively charged dense center of an atom

   noun.object

   Source: WordNet 3.0

3. a small group of indispensable persons or things

   noun.group

   Synonyms core core group

   Source: WordNet 3.0

4. (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

   noun.object

   Source: WordNet 3.0

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

   noun.body

   Source: WordNet 3.0

6. the central structure of the lens that is surrounded by the cortex

   noun.body

   Synonyms lens nucleus

   Source: WordNet 3.0

7. A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; -- used both literally and figuratively.

   noun

   Source: webster1913