NUCLEUS • DICTIONARY ONE.COM • Definition of Nucleus

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/nˈukliəs/ Listen

noun

Nucleus n. (pl. E. nucleuses, L. nuclei)

1.

A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; used both literally and figuratively. "It must contain within itself a nucleus of truth."

2.

(Astron.) The body or the head of a comet.

3.

(Bot.)

(a)

An incipient ovule of soft cellular tissue.

(b)

A whole seed, as contained within the seed coats.

4.

(Biol.) A body, usually spheroidal, in a eukaryotic cell, distinguished from the surrounding protoplasm by a difference in refrangibility and in behavior towards chemical reagents, which contains the chromosomal genetic material, including the chromosomal DNA. It is more or less protoplasmic, and consists of a clear fluid (achromatin) through which extends a network of fibers (chromatin) in which may be suspended a second rounded body, the nucleolus (see Nucleoplasm). See Cell division, under Division. Note: The nucleus is sometimes termed the endoplast or endoblast, and in the protozoa is supposed to be concerned in the female part of the reproductive process. See Karyokinesis.

5.

(Zool.)

(a)

The tip, or earliest part, of a univalve or bivalve shell.

(b)

The central part around which additional growths are added, as of an operculum.

(c)

A visceral mass, containing the stomach and other organs, in Tunicata and some mollusks.

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Etymology of 'Nucleus'

Collaborative International Dictionary of English 0.48

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"Nucleus" Quotes from Famous Books

... whose real founder is said to have been the late Henry George, was formed in the '70s by newspaper writers and men working in the arts or interested in them. It had grown to a membership of 750. It still kept for its nucleus painters, writers, musicians and actors, amateur and professional. They were a gay group of men, and hospitality was their avocation. Yet the thing which set this club off from all others in the world was the midsummer ...

— The City That Was - A Requiem of Old San Francisco • Will Irwin

... increased knowledge in Geology during the present century, owing to the greater attention of philosophers to the situations of the different materials, which compose the strata of the earth, as well as to their chemical properties, it seems clearly to appear, that the nucleus of the globe beneath the ocean consisted of granite; and that on this the great beds of limestone were formed from the shells of marine animals during the innumerable primeval ages of the world; and that whatever strata lie on these beds of limestone, or on ...

— The Temple of Nature; or, the Origin of Society - A Poem, with Philosophical Notes • Erasmus Darwin

... of Mr. Van Buren that the English Abolitionists first began to propagate their doctrines in the Northern States, where the nucleus of an anti-slavery party was soon formed. This alarmed the Southerners, who, under the lead of Mr. Calhoun, threatened disunion if their "peculiar institution" was not let alone. The gifted South Carolinian having in January, 1838, paid a ...

— Perley's Reminiscences, Vol. 1-2 - of Sixty Years in the National Metropolis • Benjamin Perley Poore

... that I was too cowardly to come forward and take my share of this public notice, so I turned away to the inn and there awaited her coming. Indeed, she has seldom attempted to sketch without finding herself the nucleus of ...

— Passages From the French and Italian Notebooks, Complete • Nathaniel Hawthorne

... to that of putting off an evil day which some time must be endured—the atoms group themselves into molecules. In their turn the molecules go forth to war, capturing or being captured; the vibrations of the slaves always being forced to synchronise with those of their conquerors. The nucleus of the gas of a primal metal is now complete, and the foundation of a solar system—paltry molecule of the Universe as it is—is laid. Thereafter, the rest is easily followed. It is described in your school books, and must ...

— The Crack of Doom • Robert Cromie

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