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| nu·cle·us [ nklee əss ] (plural nu·cle·i [ nklee ] or nu·cle·us·es) |
noun |
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| Definition: |
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1. important element: a central or most important item or part that has others grouped or built around it
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2. physics central region of atom: the positively charged central region of an atom, consisting of protons and neutrons and containing most of the mass
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3. cell biology central part of living cell: the central body, usually spherical, within a eukaryotic cell, that is a membrane-encased mass of protoplasm containing the chromosomes and other genetic information necessary to control cell growth and reproduction
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4. astronomy central part of nebula or galaxy: the central brighter portion of a nebula or galaxy
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5. astronomy core of comet head: the central core in the head of a comet, consisting of ice, frozen gases, and dust
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6. chemistry stable atoms in molecule: a stable group of atoms in a molecule, e.g. a benzene ring, that forms the base structure of many compounds and remains unchanged in chemical reactions
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7. anatomy group of nerve cells: a group of nerve cells in the central nervous system or a small mass of gray matter in the brain that has a specialized function
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8. phonetics most resonant part of syllable: the most resonant part of a syllable, usually the vowel
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| [Early 18th century. < Latin, "kernel" < nuc- "nut"] |
