nucleus (redirected from Fastigial nucleus)

nu·cle·us  (nkl-s, ny-)

n. pl. nu·cle·i (-kl-) or nu·cle·us·es

1. A central or essential part around which other parts are gathered or grouped; a core: the nucleus of a city.

2. Something regarded as a basis for future development and growth; a kernel: a few paintings that formed the nucleus of a great art collection.

3. Biology A large, membrane-bound, usually spherical protoplasmic structure within a living cell, containing the cell's hereditary material and controlling its metabolism, growth, and reproduction.

4. Botany

a. The central kernel of a nut or seed.

b. The center of a starch granule.

5. Anatomy A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.

6. Physics The positively charged central region of an atom, composed of protons and neutrons and containing almost all of the mass of the atom.

7. Chemistry A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.

8. Astronomy

a. The central portion of the head of a comet.

b. The central or brightest part of a nebula or galaxy.

9. Meteorology A particle on which water vapor molecules accumulate in free air to form a droplet or ice crystal.

10. Linguistics The part of a syllable having the greatest sonority. In the word middlemost (mdl-mst) the nuclei of the three syllables are (), (l), and (); in the Czech word krk ("neck"), the nucleus is (r).

---

[Latin nuculeus, nucleus, kernel, from nucula, little nut, diminutive of nux, nuc-, nut.]

---

nucleus

Noun

pl -clei

1. Physics the positively charged centre of an atom, made of protons and neutrons, about which electrons orbit

2. a central thing around which others are grouped

3. a centre of growth or development: the nucleus of a new relationship

4. Biol the part of a cell that contains the chromosomes and associated molecules that control the characteristics and growth of the cell

5. Chem a fundamental group of atoms in a molecule serving as the base structure for related compounds [Latin: kernel]

---

nucleus  (nkl-s)

Plural nuclei (nkl-)

1. 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. See more at atom.

2. 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. See more at cell.

3.

a. The solid central part of a comet, typically several kilometers in diameter and composed of ice, frozen gases, and embedded chunks of rock and dust. It is the permanent part of a comet from which the coma and tail are generated as the comet approaches the Sun. See more at comet.

b. See galactic nucleus.

---

Nucleus a central mass or number; a collection of persons or items to which addition will be made.

Examples: nucleus of epic cycles, 1835; of a library, 1875; of pain and pleasure, 1876; of physicists—Lipton, 1970; of fine thoughts, 1820.

Thesaurus

Noun	1.	nucleus - a part of the cell containing DNA and RNA and responsible for growth and reproduction cell nucleus, karyon cell - (biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals pronucleus - the nucleus of the ovum or sperm after fertilization but before they fuse to form the nucleus of the zygote karyoplasm, nucleoplasm - the protoplasm that constitutes the nucleus of a cell nucleole, nucleolus - a small round body of protein in a cell nucleus; such organelles contain RNA and are involved in protein synthesis chromatin, chromatin granule - the readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins; during mitotic division it condenses into chromosomes achromatin - the part of a cell nucleus that is relatively uncolored by stains or dyes linin - an obsolete term for the network of viscous material in the cell nucleus on which the chromatin granules were thought to be suspended chromosome - a threadlike strand of DNA in the cell nucleus that carries the genes in a linear order; "humans have 22 chromosome pairs plus two sex chromosomes" cell organ, cell organelle, organelle - a specialized part of a cell; analogous to an organ; "the first organelle to be identified was the nucleus" subthalamic nucleus - an oval mass of grey matter located in the caudal part of the subthalamus; associated with the striate body
	2.	nucleus - the positively charged dense center of an atom midpoint, centre, center - a point equidistant from the ends of a line or the extremities of a figure nucleon - a constituent (proton or neutron) of an atomic nucleus atom - (physics and chemistry) the smallest component of an element having the chemical properties of the element
	3.	nucleus - a small group of indispensable persons or things; "five periodicals make up the core of their publishing program" core, core group set - a group of things of the same kind that belong together and are so used; "a set of books"; "a set of golf clubs"; "a set of teeth" cadre - a nucleus of military personnel capable of expansion
	4.	nucleus - (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 astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole midpoint, centre, center - a point equidistant from the ends of a line or the extremities of a figure comet - (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit
	5.	nucleus - any histologically identifiable mass of neural cell bodies in the brain or spinal cord neural structure - a structure that is part of the nervous system dentate nucleus - a large laminar nucleus of grey matter within the white matter of each cerebral hemisphere
	6.	nucleus - the central structure of the lens that is surrounded by the cortex lens nucleus anatomical structure, bodily structure, body structure, complex body part, structure - a particular complex anatomical part of a living thing; "he has good bone structure"

---

nucleus

noun centre, heart, focus, basis, core, pivot, kernel, nub

Translations

nucleus [pl nuclei] [ˈnjuːklɪəs, ˈnjuːklɪaɪ] n → núcleo

---

nucleus [nuclei , pl ] [ˈnjuːklɪəs, ˈnjuːklɪaɪ] n → noyau m

---

nucleus [ˈnjuːklɪəs] [nuclei , pl ] n → Kern m

---

nucleus [pl nuclei] [ˈnjuːklɪəs, ˈnjuːklɪaɪ] n → nucleo