Nucleus NU'CLEUS, n. [L. a nut.]
1. Properly, the kernel of a nut; but in usage, any body about which matter is collected.
2. The body of a comet, called also its head, which appears to be surrounded with light.

nucleus n 1: a part of the cell containing DNA and RNA and responsible for growth and reproduction [syn: nucleus, cell nucleus}, karyon] 2: the positively charged dense center of an atom 3: a small group of indispensable persons or things; "five periodicals make up the core of their publishing program" [syn: core, nucleus, core group] 4: (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 5: any histologically identifiable mass of neural cell bodies in the brain or spinal cord 6: the central structure of the lens that is surrounded by the cortex [syn: lens nucleus, nucleus]

nucleus 1708, from L. nucleus "kernel," from nucula "little nut," dim. of nux (gen. nucis) "nut," from PIE *knu(k) "lump." At first in Eng. "head of a comet;" use in reference to cells first recorded 1831. Modern atomic meaning is 1912, first by Ernest Rutherford, though theoretical use for "central point of an atom" is from 1844.

nucleus
n. (pl. nuclei)
1 a the central part or thing round which others are collected. b the kernel of an aggregate or mass.
2 an initial part meant to receive additions.
3 Astron. the solid part of a comet's head.
4 Physics the positively charged central core of an atom that contains most of its mass.
5 Biol. a large dense organelle of eukaryotic cells, containing the genetic material.
6 a discrete mass of grey matter in the central nervous system.
Etymology: L, = kernel, inner part, dimin. of nux nucis nut

nucleus (nuclei) 1. The nucleus of an atom or cell is the central part of it. Neutrons and protons are bound together in the nucleus of an atom. N-COUNT: usu with supp 2. The nucleus of a group of people or things is the small number of members which form the most important part of the group. The Civic Movement could be the nucleus of a centrist party of the future. = core N-COUNT: usu the N of n

nucleus ˈnju:klɪəs n. (pl. nuclei) 1 a the central part or thing round which others are collected. b the kernel of an aggregate or mass. 2 an initial part meant to receive additions. 3 Astron. the solid part of a comet's head. 4 Physics the positively charged central core of an atom that contains most of its mass. 5 Biol. a large dense organelle of eukaryotic cells, containing the genetic material. 6 a discrete mass of grey matter in the central nervous system. [L, = kernel, inner part, dimin. of nux nucis nut]

Nucleus \Nu"cle*us\, n.; pl. E. Nucleuses, L. Nuclei. [L., a kernel, dim. fr. nux, nucis, nut. Cf. Newel post.] 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. --I. Taylor. 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 cell or a protozoan, distinguished from the surrounding protoplasm by a difference in refrangibility and in behavior towards chemical reagents. 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.

nucleus n. Kernel, core, centre.

nucleus ˈnju:klɪəs n. core, heart, centre, kernel, pith, focus, nub: We already have the nucleus of a very good team. The market square was the nucleus around which many towns were built.

112 Moby Thesaurus words for "nucleus": Anlage, Kern, NMR, alpha particle, antibaryon, antilepton, antimeson, atomic nucleus, atomic particle, axiom, axis, baryon, basichromatin, beta particle, bud, center, center of action, center of gravity, centroid, centrum, chromatin, chromatin strands, core, dead center, diameter, diaphragm, egg, electron, elementary particle, elixir, embryo, epicenter, equator, essence, essential, flower, focus, fundamental, germ, germen, gist, gravamen, heart, heterochromatin, hub, hypostasis, inner essence, interior, karyosome, karyotin, kernel, lepton, loins, macronucleus, marrow, mean, meat, median, medulla, meganucleus, meson, metacenter, micronucleus, middle, midmost, midriff, midst, nave, navel, neutron, nub, nuclear force, nuclear magnetic resonance, nuclear particle, nuclear resonance, nucleolus, nucleon, nucleosynthesis, nuts and bolts, omphalos, ovum, photon, pith, pivot, plasmosome, postulate, principle, proton, quid, quiddity, quintessence, rudiment, sap, seed, soul, spark, spermatozoon, spirit, storm center, strangeness, strong interaction, stuff, substance, the nitty-gritty, thick, thick of things, triton, umbilicus, valence electron, waist, waistline, zone

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