(physics and chemistry) the smallest component of an element having the chemical properties of the element | a part of the cell containing DNA and RNA and responsible for growth and reproduction |
(nontechnical usage) a tiny piece of anything | any histologically identifiable mass of neural cell bodies in the brain or spinal cord |
| the central structure of the lens that is surrounded by the cortex |
| a small group of indispensable persons or things |
| the positively charged dense center of an atom |
| (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 |