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[doh-meyn] /doʊˈmeɪn/
a field of action, thought, influence, etc.:
the domain of science.
the territory governed by a single ruler or government; realm.
a realm or range of personal knowledge, responsibility, etc.
a region characterized by a specific feature, type of growth or wildlife, etc.:
We entered the domain of the pine trees.
  1. the set of values assigned to the independent variables of a function.
  2. region (def 11a).
  2. the top level in a domain name, indicating the type of organization, geographical location, or both, and officially designated in the suffix, as .edu for institutions of higher education.
Physics. one of many regions of magnetic polarity within a ferromagnetic body, each consisting of a number of atoms having a common polarity, and collectively determining the magnetic properties of the body by their arrangement.
Crystallography. a connected region with uniform polarization in a twinned ferroelectric crystal.
Origin of domain
1595-1605; < French domaine, alteration, by association with Latin dominium dominium, of Old French demeine < Late Latin dominicum, noun use of neuter of Latin dominicus of a master, equivalent to domin(us) lord + -icus -ic
Related forms
domanial, adjective Unabridged
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Examples from the Web for domain
Contemporary Examples
Historical Examples
  • In no branch of medicine or sociology is this fallacy more fruitful of error than in the domain of mental disease.


    The Lost Princess of Oz L. Frank Baum
  • The variety of combinations in the domain of possible things is infinite.

    The Mason-bees J. Henri Fabre
  • The domain of alternatives constitutes the civilization of illiteracy.

  • It is an attempt to carry the methods of science into the domain of philosophy, to substitute science for philosophy.

    Evolution Frank B. Jevons
British Dictionary definitions for domain


land governed by a ruler or government
land owned by one person or family
a field or scope of knowledge or activity
a region having specific characteristics or containing certain types of plants or animals
(Austral & NZ) a park or recreation reserve maintained by a public authority, often the government
(law) the absolute ownership and right to dispose of land See also demesne, eminent domain
  1. the set of values of the independent variable of a function for which the functional value exists: the domain of sin x is all real numbers Compare range (sense 8a)
  2. any open set containing at least one point
(logic) another term for universe of discourse domain of quantification
(philosophy) range of significance (esp in the phrase domain of definition)
(physics) Also called magnetic domain. one of the regions in a ferromagnetic solid in which all the atoms have their magnetic moments aligned in the same direction
(computing) a group of computers, functioning and administered as a unit, that are identified by sharing the same domain name on the internet
(biology) Also called superkingdom. the highest level of classification of living organisms. Three domains are recognized: Archaea (see archaean), Bacteria (see bacteria), and Eukarya (see eukaryote)
(biochem) a structurally compact portion of a protein molecule
Word Origin
C17: from French domaine, from Latin dominium property, from dominus lord
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Word Origin and History for domain

early 15c., in Scottish, from Middle French domaine "domain, estate," from Old French demaine "lord's estate," from Latin dominium "property, dominion," from dominus "lord, master, owner," from domus "house" (see domestic). Form influenced in Old French by Medieval Latin domanium "domain, estate." Internet domain name attested by 1985.

Online Etymology Dictionary, © 2010 Douglas Harper
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domain in Medicine

domain do·main (dō-mān')

The American Heritage® Stedman's Medical Dictionary
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domain in Science
  1. Mathematics The set of all values that an independent variable of a function can have. In the function y = 2x, the set of values that x (the independent variable) can have is the domain. Compare range.

  2. Computer Science A group of networked computers that share a common communications address.

  3. Biology A division of organisms that ranks above a kingdom in systems of classification that are based on shared similarities in DNA sequences rather than shared structural similarities. In these systems, there are three domains: the archaea, the bacteria, and the eukaryotes.

  4. Physics A region in a ferromagnetic substance in which the substance is magnetized with the same polarization throughout.

The American Heritage® Science Dictionary
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domain in Technology

1. A group of computers whose fully qualified domain names (FQDN) share a common suffix, the "domain name".
The Domain Name System maps hostnames to Internet address using a hierarchical namespace where each level in the hierarchy contributes one component to the FQDN. For example, the computer is in the domain, which is in the domain, which is in the domain, which is in the uk top-level domain.
A domain name can contain up to 67 characters including the dots that separate components. These can be letters, numbers and hyphens.
2. An administrative domain is something to do with routing.
3. Distributed Operating Multi Access Interactive Network.
4. In the theory of functions, the set of argument values for which a function is defined.
See domain theory.
5. A specific phase of the software life cycle in which a developer works. Domains define developers' and users' areas of responsibility and the scope of possible relationships between products.
6. The subject or market in which a piece of software is designed to work.

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