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noun do·main \dō-ˈmān, də-\

Simple Definition of domain

  • : the land that a ruler or a government controls

  • : an area of knowledge or activity

  • computers : a section of the Internet that is made up of computers or sites that are related in some way (such as by use or source)

Source: Merriam-Webster's Learner's Dictionary

Full Definition of domain

  1. 1 a :  complete and absolute ownership of land — compare eminent domain b :  land so owned

  2. 2 :  a territory over which dominion is exercised

  3. 3 :  a region distinctively marked by some physical feature <the domain of rushing streams, tall trees, and lakes>

  4. 4 :  a sphere of knowledge, influence, or activity <the domain of art>

  5. 5 :  the set of elements to which a mathematical or logical variable is limited; specifically :  the set on which a function is defined

  6. 6 :  any of the small randomly oriented regions of uniform magnetization in a ferromagnetic substance

  7. 7 :  integral domain

  8. 8 :  the highest taxonomic category in biological classification ranking above the kingdom

  9. 9 :  any of the three-dimensional subunits of a protein that are formed by the folding of its linear peptide chain and that together make up its tertiary structure

  10. 10 :  a subdivision of the Internet consisting of computers or sites usually with a common purpose (as providing commercial information) and denoted in Internet addresses by a unique abbreviation (as com or gov); also :  domain name

Examples of domain in a sentence

  1. The forest is part of the king's domain.

  2. My sister is the math expert in the family, but literature is my domain.

  3. Childcare is no longer solely a female domain.

Origin and Etymology of domain

alteration of Middle English demayne, from Anglo-French demeine, from Latin dominium, from dominus

First Known Use: 15th century

Rhymes with domain

abstain, again, air lane, airplane, amain, arcane, arraign, attain, Bahrain, Bassein, Beltane, biplane, birdbrain, block plane, bloodstain, boat train, brain drain, bugbane, campaign, champagne, champaign, Champlain, checkrein, chicane, chilblain, choke chain, chow mein, cinquain, cocaine, Cockaigne, Coltrane, coxswain, complain, constrain, contain, cordwain, cowbane, crackbrain, demesne, deplane, destain, detain, detrain, devein, disdain, distain, distrain, dogbane, drivetrain, dumb cane, edge-grain, Elaine, enchain, enplane, entrain, ethane, explain, eyestrain, fast lane, fleabane, floatplane, floodplain, food chain, forebrain, Fort Wayne, Gawain, germane, Great Dane, grosgrain, half plane, henbane, hindbrain, house-train, humane, Hussein, Igraine, immane, inane, ingrain, insane, jack plane, lamebrain, left brain, lightplane, lo mein, long-chain, Lorraine, maintain, marchpane, membrane, methane, midbrain, migraine, Montaigne, montane, moraine, mortmain, Moulmein, mundane, neck-rein, New Spain, obtain, octane, ordain, pertain, plain-Jane, profane, propane, ptomaine, purslane, quatrain, raise Cain, refrain, remain, restrain, retain, retrain, right brain, romaine, sailplane, sea-lane, seaplane, seatrain, split-brain, sustain, tailplane, tearstain, terrane, Touraine, towplane, triplane, Ukraine, unchain, urbane, vervain, vicereine, villein, volplane, warplane, wave train, wolfsbane

DOMAIN Defined for Kids


noun do·main \dō-ˈmān\

Definition of domain for Students

  1. 1 :  land under the control of a ruler or a government

  2. 2 :  a field of knowledge or activity <the domain of science>

  3. 3 :  domain name

Word Root of domain

The Latin word dominus, meaning “master,” gives us the root domin. Words from the Latin dominus have something to do with being another's master. To dominate is to have power and control over as if being someone's master. A domain, or land under the control of a government, is a land with a particular master or ruler. Dominion is controlling power, similar to the power of a master over others.

Medical Dictionary


noun do·main \dō-ˈmān, də-\

Medical Definition of domain

  1. 1:  any of the three-dimensional subunits of a protein that together make up its tertiary structure, that are formed by folding its linear peptide chain, and that are variously considered to be the basic units of protein structure, function, and evolution <immunoglobulin light chains have two domains and heavy chains have four or five domains, depending on class—Journal of the American Medical Association>

  2. 2:  the highest taxonomic category in biological classification ranking above the kingdom

Seen and Heard

What made you want to look up domain? Please tell us where you read or heard it (including the quote, if possible).


an indentation on an edge or a surface

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