domain

noun

do·​main dō-ˈmān 

də-

1

law

a

: complete and absolute (see absolute sense 3) ownership of land

our highways and roads have been in the domain of state and local governments

—T. H. White b. 1915

compare eminent domain

b

: land so owned

2

: a territory over which dominion (see dominion sense 2) is exercised

The forest is part of the king's domain.

3

: a region distinctively marked by some physical feature

a domain of rushing streams, tall trees, and lakes

4

: a sphere (see sphere sense 4b) of knowledge, influence, or activity

the domain of biblical scholarship

outside the domain of city police

5

mathematics : the set of elements (see element sense 2b(3)) to which a mathematical or logical variable is limited

specifically : the set on which a function (see function entry 1 sense 5a) is defined

6

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

7

mathematics : integral domain

8

biology : the highest taxonomic category in biological classification ranking above the kingdom (see kingdom sense 4b)

9

biochemistry : 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 (see tertiary entry 1 sense 3c) structure

10

computers : a subdivision of the Internet consisting of computers or sites usually with a common purpose (such as providing commercial information) and denoted in Internet addresses by a unique abbreviation (such as com for commercial sites or gov for government sites)

The domain ca is used for sites located in Canada.

also : domain name

Our domain is Merriam-Webster.com.

Synonyms

• area
• arena
• bailiwick
• barony
• business
• circle
• demesne
• department
• discipline
• element
• fief
• fiefdom
• field
• firmament
• front
• game
• kingdom
• line
• precinct
• province
• realm
• specialty
• sphere
• terrain
• walk

Examples of domain in a Sentence

The forest is part of the king's domain.

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

Childcare is no longer solely a female domain.

Recent Examples on the Web

Think of an organization in any domain that has achieved something big in the last few decades. —Adam Fayed, Forbes, 11 Dec. 2024

The imposter site was created by a company called Namecheap Inc. on Nov. 22, a week before the Instagram video was shared, according to the domain information tool WHOIS. —Hannah Hudnall, USA TODAY, 9 Dec. 2024

This iteration of Yama Sakura is also set to focus on the integration of multi-domain operations across land, air, sea, space and cyber domains. —Paul Du Quenoy, Newsweek, 9 Dec. 2024

Winning an election does not give anyone domain over the truth. —Bill Goodykoontz, The Arizona Republic, 8 Dec. 2024

Word History

Etymology

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

First Known Use

15th century, in the meaning defined at sense 1a

Phrases Containing domain

• domain name
• eminent domain
• integral domain
• in the public domain
• public domain
• the public domain

Kids Definition

domain

noun

do·​main dō-ˈmān 

də-

1

: a territory over which control is exercised

2

: an area of influence, knowledge, or activity

3

: a small region of a magnetic substance that contains atoms all lined up in the same direction and behaving like a single tiny magnet

4

: the highest category in the scientific classification of living things ranking above the kingdom

5

: a main subdivision of the Internet

also : domain name

Etymology

from early French demeine "land one owns," from Latin dominium "rule, ownership," from dominus "master, owner" — related to condominium, dominate, dominion

Medical Definition

domain

noun

do·​main dō-ˈmān, də- 

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

—The Journal of the American Medical Association

2

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