[ doh-meyn ]
See synonyms for: domaindomains on

  1. a field of action, thought, influence, etc.: the domain of science.

  2. the territory governed by a single ruler or government; realm.

  1. a realm or range of personal knowledge, responsibility, etc.

  2. a region characterized by a specific feature, type of growth or wildlife, etc.: We entered the domain of the pine trees.

  3. Law. land to which there is superior title and absolute ownership.

  4. Biology. a taxonomic category of the highest rank, just above kingdom, grouping together all forms of life having certain fundamental characteristics in common: in the three-domain system of classification adopted by many biologists, separate domains are assigned to the archaea (Archaea), bacteria (Bacteria), and eukaryotes (Eukaryota).

  5. Mathematics.

    • the set of values assigned to the independent variables of a function.

  6. Computers.

    • a group of computers and devices on a network that are administered under the same protocol.

    • (on the internet) one or more computers or computer networks under the same administrative control, identified by a domain name or any of its discrete parts.

  7. 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.

  8. Crystallography. a connected region with uniform polarization in a twinned ferroelectric crystal.

Origin of domain

First recorded in 1595–1605; from French domaine, alteration (by association with Latin dominium “right of ownership, property”) of Old French demeine, from Late Latin dominicum, noun use of neuter of Latin dominicus “of a master,” equivalent to domin(us) “lord, master” + -icus; see origin at dominium, -ic

Other words from domain

  • do·ma·ni·al, adjective

Words Nearby domain Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use domain in a sentence

British Dictionary definitions for domain


/ (dəˈmeɪn) /

  1. land governed by a ruler or government

  2. land owned by one person or family

  1. a field or scope of knowledge or activity

  2. a region having specific characteristics or containing certain types of plants or animals

  3. Australian and NZ a park or recreation reserve maintained by a public authority, often the government

  4. law the absolute ownership and right to dispose of land: See also demesne, eminent domain

  5. maths

    • 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 (def. 8a)

    • any open set containing at least one point

  6. logic another term for universe of discourse domain of quantification

  7. philosophy range of significance (esp in the phrase domain of definition)

  8. Also called: magnetic domain physics one of the regions in a ferromagnetic solid in which all the atoms have their magnetic moments aligned in the same direction

  9. computing a group of computers, functioning and administered as a unit, that are identified by sharing the same domain name on the internet

  10. Also called: superkingdom biology the highest level of classification of living organisms. Three domains are recognized: Archaea (see archaean), Bacteria (see bacteria), and Eukarya (see eukaryote)

  11. biochem a structurally compact portion of a protein molecule

Origin of domain

C17: from French domaine, from Latin dominium property, from dominus lord

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for domain


[ dō-mān ]

  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.

  1. 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.

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

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.