1.Definition: (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

Category: Objects

2.Definition: a part of the cell containing DNA and RNA and responsible for growth and reproduction

Related Noun(s):karyon

Category: General

3.Definition: a small group of indispensable persons or things

Related Noun(s):core

Category: General

4.Definition: any histologically identifiable mass of neural cell bodies in the brain or spinal cord

Category: General

5.Definition: the central structure of the lens that is surrounded by the cortex

Category: General

6.Definition: the positively charged dense center of an atom

Category: Objects