nuclei

(noun) a part of the cell containing DNA and RNA and responsible for growth and reproduction. Synonyms: nucleus, cell nucleus, karyon.

(noun) the positively charged dense center of an atom. Synonyms: nucleus.

(noun) a small group of indispensable persons or things. Synonyms: core, nucleus, core group. Example: "Five periodicals make up the core of their publishing program."

(noun) (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. Synonyms: nucleus.

(noun) any histologically identifiable mass of neural cell bodies in the brain or spinal cord. Synonyms: nucleus.

(noun) the central structure of the lens that is surrounded by the cortex. Synonyms: lens nucleus, nucleus.