NucleinThe term used by Friedrich Miescher to describe the nuclear material he discovered in 1869, which today is known as DNA.
nucleo-cytoplasmic ratioIn a cell, the ratio of nuclear to cytoplasmic volume. This ratio is high in meristematic cells and low in differentiated cells.
nucleolar organizer region(Abbreviation: NOR). A chromosomal segment containing a large array of genes that encode ribosomal RNA; located at the secondary constriction of specific…
NucleonicsThe science, technology, and application of nuclear energy.
nucleoplasmThe non-staining or slightly chromophilic, liquid or semi-liquid, ground substance of the interphase nucleus and which fills the nuclear space around the…
nucleoproteinConjugated protein composed of nucleic acid and protein; the material of which the chromosomes are made.
NucleosideA building block of DNA and RNA, consisting of a nitrogenous base linked to a five carbon sugar. (See Nucleoside analog.)
Nucleoside analogA synthetic molecule that resembles a naturally occuring nucleoside, but that lacks a bond site needed to link it to an adjacent nucleotide.
nucleoside analogueA synthetic molecule that resembles a naturally occurring nucleoside.
nucleosomeSpherical sub-units of eukaryotic chromatin that are composed of a core particle consisting of an octamer of histones (two molecules each of histones H2a…
NucleosynthesisThe process by which atoms are formed by the coming together of subatomic particles and other smaller atoms.
Nucleotide(NOO-klee-oh-TIDE) A building block for nucleic acids (the molecules inside cells that carry genetic information).
Nucleus(NOO-klee-us) In biology, the structure in a cell that contains the chromosomes.
Nucleus/Nuclei(plural- nuclei; adjective- nuclear ) The center of an atom. Nearly 100% percent of the mass of an atom is contained in the nucleus.
NuclideAny species of atom that exists for a measurable length of time. A nuclide can be distinguished by its atomic weight, atomic number, and energy state.
NUICCSNORAD and USSPACECOM Integrated Command and Control System.
NukeA spell that can inflict a large amount of damage quickly.
nullThe null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters.
null alleleAn allele which produces no functional gene product.
null characterThe \u0000 character. Care should be taken not to confuse this with the null reference.
null character (NUL)In transmission systems, a control character (a) that is used to accomplish media-fill stuffing or a time-fill stuffing in storage device or in a data…
Null hypothesisThe assumption that any observed difference between two samples of a statistical population is purely accidental and not due to systematic causes.
null listA "list value" with zero elements, represented in Perl by ().
null objectA null object is one whose version ID is null. Amazon S3 adds a null object to a bucket when versioning for that bucket is suspended.
null referenceA value used to mean, `no object'. Used when an object reference variable is not referring to an object.
null stringA "string" containing no characters, not to be confused with a string containing a "null character", which has a positive length and is "true".
null valueThe absence of a value. If a particular column of a row in a table is null, that means there is no value stored. Null is not the same as blank or zero.
Nulla bonaReturn made upon execution by the sheriff or court officer when he/she has found no leviable goods.
nullificationA state's refusal to recognize or obey a federal law.
nullisomyAn otherwise diploid cell or organism lacking both members of a homologous chromosome pair.
NUMA (Non-Uniform Memory Access)describes a system architecture in which the machine is organized into a series of nodes containing processors and memory.
number baseThe base used to interpret numerical characters. Decimal notation is base 10 and binary notation is base 2, for instance.
number portabilityA term used to describe the capability of individuals, businesses and organizations to retain their existing telephone number(s) and the same quality of…
numbering plan area (NPA)1. A defined geographic area identified by a unique three- digit code used in the North American Number Plan Area. [T1.207-1998] [T1.
numeric contextThe situation in which an expression is expected by its surroundings (the code calling it) to return a number. See also "context" and "string context".
numeric filing systemAny classification system for arranging records that is based on numbers See also alphabetic filing system.
numerical aperture (NA)The sine of the vertex angle of the largest cone of meridional rays that can enter or leave an optical system or element, multiplied by the refractive…
numerical aperture lossA loss of optical power that occurs at a splice or a pair of mated connectors when the numerical aperture of the "transmitting" fiber exceeds that of the…
Numerical ForecastingA computer forecast or prediction based on equations governing the motions and the forces affecting motion of fluids.
Numerical LimitationsTotal immigration into the U.S. is limited to 675,000 persons each year. This figure is divided into 3 different categories of immigrants…
Numerical Weather PredictionSame as Numerical Forecasting; a computer forecast or prediction based on equations governing the motions and the forces affecting motion of fluids.
NumerousA National Weather Service convective precipitation descriptor for a 60 or 70 percent chance of measurable precipitation (0.01 inch).
Nunc pro tuncNow for then; acts allowed with retroactive effect.
nurseA health professional trained to care for people who are ill or disabled.
nurse cultureCulturing cells from a suspension culture on a raft of filter paper above a callus tissue piece (nurse tissue).
Nurse plantsMature plants that create favorable conditions for seeds to germinate and for seedlings to survive and grow.
Nursing HomeA place that gives care to people who have physical or mental disabilities and need help with activities of daily living (such as taking a bath, getting…
nutraceuticalA food or dietary supplement that is believed to provide health benefits.
nutriceuticalA conventional food product that has been modified (potentially by genetic engineering) to have improved nutritional characteristics and/or pharmaceutical…
nutrient(NOO-tree-ent) A chemical compound (such as protein, fat, carbohydrate, vitamin, or mineral) contained in foods.
nutrient cycleThe passage of a nutrient or element through an ecosystem, including its assimilation and release by various organisms and its transformation into various…
nutrient deficiencyAbsence or insufficiency of an essential factor for normal growth and development.
nutrient film technique(Abbreviation: NFT). A hydroponic technique used to grow plants. NFT delivers a thin film of water or nutrient solution either continuously or through…
nutrient gradientA diffusion gradient of nutrients and gases that develops in tissues where only a portion of the tissue is in contact with the medium.
nutrient medium(pl.: nutrient media) A solid, semi-solid or liquid formulation for in vitro cell or tissue growth.
NutrientsAnimal, vegetable, or mineral substance which sustains individual organisms and ecosystems.
nutrition(noo-TRIH-shun) The taking in and use of food and other nourishing material by the body. Nutrition is a 3-part process. First, food or drink is consumed.
nutrition therapy(noo-TRIH-shun THAYR-uh-pee) Treatment based on nutrition. It includes checking a person's nutrition status, and giving the right foods or nutrients to…
nutritional counseling(noo-TRIH-shuh-nul KOWN-suh-ling) A process by which a health professional with special training in nutrition helps people make healthy food choices and…
nutritional status(noo-TRIH-shuh-nul STA-tus) The state of a person's health in terms of the nutrients in his or her diet.
nutritional supplement(noo-TRIH-shuh-nul SUH-pleh-ment) A product that is added to the diet. A nutritional supplement is taken by mouth, and usually contains one or more…
nutritionistA health professional with special training in nutrition who can help with dietary choices. Also called dietitian.
NutsThe best possible hand given the board. If the board is K♠-J ♦-T♠-4 ♠-2♥, then A ♠-X♠ is the nuts.
NVShort for Nevada, no part of which will ever be confused with civilization. NV also means an internal floating-point Numeric Value of the type a "scalar"…
NVANegative Vorticity Advection - the advection of lower values of vorticity into an area.
NVFAILSoftware that warns you of compromised database validity and automatically renames the database so that it does not restart automatically.
NWRNOAA Weather Radio - "the voice of the National Weather Service" - NOAA Weather Radio broadcasts National Weather Service warnings, watches, forecasts and…
NWSNational Weather Service. An agency of the Federal Government within the Department of Commerce, National Oceanic and Atmospheric Administration, which is…