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domain

/doʊˈmeɪn//dəˈmeɪn/·noun
an area of activity, knowledge, or control
Fig. 1 — I watch the knight stand on its square, and all at once the squares it could spring to light up around it — that crooked L thrown in every direction, the ground it commands from right here.
01Definition

A domain is the field over which someone or something holds sway — a sphere of rule, of expertise, or of a whole discipline. It is marked off from the world outside its boundary; close to realm, but wider in everyday use, it can name a monarch's lands, a branch of science, or any defined scope of control. Online it has a narrower technical sense: the named address a website lives at. The constant is a bounded territory that belongs to, or is governed by, one thing.

02In use
  • iStatistics lies outside her domain, so she defers to colleagues who can scrutinize the data properly.
  • iiMost research stays within one narrow domain and rarely strays past its edge.
  • iiiOnline, a single misspelled domain name can send your visitors somewhere else entirely.
03Collocations
  • the public domain
  • outside my domain
  • a domain of knowledge
  • the domain of experts
  • in the digital domain

Family dominion (noun)

04Relations

=field, sphere, realm, territory, province

05Compared
PairThe difference
domain vs realma field of control or expertise (or a web address) → domain; a kingdom or grand bounded world → realm.
06TOEFL & IELTS

Common across academic writing for 'a field of study or activity' ('the domain of economics'). Note the senses: area of expertise, a ruler's territory, the legal 'public domain', and the web address. US stress and vowel differ slightly from UK. Trap: don't blur it with 'dominion' (rule or control itself).

07Asked
What is domain and range in maths?
For a function, the domain is the set of all allowed input values (the x's you can put in); the range is the set of outputs it actually reaches (the y's). For y = √x, the domain is numbers from zero up, since you cannot take the square root of a negative. The word keeps its core: the domain is the territory the function is allowed to work over.
What does 'public domain' mean?
The status of creative work that no one owns — because its copyright has expired or was waived — so anyone may use it freely. Shakespeare's plays and Beethoven's symphonies are in the public domain. The word's core survives: a domain here is a shared territory, open to all rather than fenced by one owner.
What is eminent domain?
The power of a government to take private property for public use — a road, a school — even without the owner's consent, provided it pays fair compensation. 'Eminent' marks it as a superior, overriding claim. It is the word's oldest sense at full strength: the state's domain, its sphere of ultimate authority, reaching over the individual's.
What does 'domain name' mean?
The named address where a website lives — the readable label, like a shop's street name, that points to a site instead of its numeric address. It is the word's narrowest modern sense: a bounded patch of the internet that belongs to one owner. The old idea of a governed, marked-off territory survives intact, just online.
What does 'domain of expertise' mean?
A person's field of knowledge or authority — 'that's outside my domain', 'the domain of neuroscience'. It is the word's central academic use: a bounded area someone commands. The scene above is that meaning in motion — a chess knight lighting up exactly the squares it governs from where it stands, its reach moving with it.
What is the difference between domain and dominion?
A domain is the territory or field itself — the land, the discipline, the scope. Dominion is the power of rule over it — sovereignty, control. A monarch's domain is the land; their dominion is the right to govern it. One is the place; the other is the authority. They share the Latin dominus, 'lord', but split the lord's estate from the lord's power.
How do you pronounce domain?
Doh-MAIN in American English, with a full first vowel; British English often reduces it to duh-MAIN. Both stress the second syllable, MAIN. The related dominion moves the stress and the vowel entirely — duh-MIN-yun — so don't let one pull the other out of shape.