Nucleus meaning

no͝oklē-əs, nyo͝o-
The nucleus is the center core of an atom that has a positive charge and that contains most of the atom's mass, or the central heart of an organization or group.

An example of a nucleus is the center core of an atom.

An example of a nucleus is the fiction department of a book publisher where most of the money is made and which is considered the heart of the publisher's organization.

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A central or essential part around which other parts are gathered or grouped; a core.

The nucleus of a city.

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The positively charged central region of an atom, composed of one or more protons and (for all atoms except hydrogen) one or more neutrons, containing most of the mass of the atom. The strong force binds the protons and neutrons, also known as nucleons , to each other, overcoming the mutual repulsion of the positively charged protons. In nuclei with many nucleons, however, the forces of repulsion may overcome the strong force, and the nucleus breaks apart in the process of radioactive decay . The protons and neutrons are arranged in the nucleus in energy levels known as shells analogous to those of the electrons orbiting the nucleus. The number of protons in the nucleus determines the atom's atomic number and its position in the Periodic Table.
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Anything serving as a center of growth or development.

The nucleus of a library.

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(chemistry) A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.
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(biology) A membrane-bound organelle within a eukaryotic cell that contains most of the cell's genetic material. DNA transcription takes place in the nucleus.
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(astron.) The bright, central part of the head of a comet.
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(chem.) In organic chemistry, a fundamental, stable arrangement of atoms, as the benzene ring, that may occur in many compounds by atomic substitution without structural change.
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(physics) The positively charged central region of an atom, composed of protons and neutrons, about which negatively charged electrons orbit. Extremely small and dense, the nucleus contains almost all of the mass of an atom.
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An organelle in the cytoplasm of eukaryotic cells (all cells except prokaryotes) that contains nearly all the cell's DNA and controls its metabolism, growth, and reproduction. The nucleus is surrounded by a pair of membranes called the nuclear envelope , which can be continuous in places with the membranes of the endoplasmic reticulum. The membranes of the nuclear envelope have interconnected pores that allow the exchange of substances with the cell's cytoplasm. The nuclear DNA is wrapped around proteins (called histones) in strands of chromatin , which exists in a matrix known as nucleoplasm (analogous to the cytoplasm outside the nucleus). Just prior to cell division, the chromatin condenses into individual chromosomes, which contain the cell's hereditary information. The nucleus also contains at least one spherical nucleolus , which mainly contains RNA and proteins and directs the construction of the cell's ribosomes.
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The core, central part (of something), round which others are assembled.
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(anatomy) A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.
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(physics) The positively charged central region of an atom, composed of protons and neutrons, about which negatively charged electrons orbit. Extremely small and dense, the nucleus contains almost all of the mass of an atom.
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(anat.) A group of nerve cells in the brain or spinal column.
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(biol.) The central, usually spherical or oval mass of protoplasm present in most plant and animal cells, containing most of the hereditary material and necessary to such functions as growth, reproduction, etc.
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(bot.) The central point in a starch grain.
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(chem., physics) The central part of an atom, the fundamental particles of which are the proton and (except for hydrogen) neutron: it carries a positive charge and constitutes almost all of the mass of the atom.
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(phonet.) The most sonorous portion of a syllable, usually a vowel.
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(anatomy) A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.
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(chemistry) A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.
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An initial part or version that will receive additions.

This collection will form the nucleus of a new library.

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(chemistry, physics) The massive, positively charged central part of an atom, made up of protons and neutrons.
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(cytology) A large organelle found in cells which contains genetic material.
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(neuroanatomy) A ganglion, cluster of many neuronal bodies where synapsing occurs.
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(linguistics) The central part of a syllable, most commonly a vowel.
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Something regarded as a basis for future development and growth; a kernel.

A few paintings that formed the nucleus of a great art collection.

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(biology) A membrane-bound organelle within a eukaryotic cell that contains most of the cell's genetic material. DNA transcription takes place in the nucleus.
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(meteorology) A particle on which water vapor molecules accumulate in free air to form a droplet or ice crystal.
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(linguistics) The part of a syllable having the greatest sonority. In the word middlemost (mĭd&STRESS;l-mōst&stress;) the nuclei of the three syllables are (ĭ), (l), and (ō); in the Czech word krk (“neck”), the nucleus is (r).
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A thing or part forming the center around which other things or parts are grouped or collected; core.
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Origin of nucleus

  • Latin nuculeus, nucleus kernel from nucula little nut diminutive of nux nuc- nut

    From American Heritage Dictionary of the English Language, 5th Edition

  • From Latin nucleus (“kernel, core"), a diminutive of nux (“nut").

    From Wiktionary