domain

/doʊˈmeɪn/
noun
  1. An area of activity, interest, or knowledge that someone controls or is involved in.
    • Politics is not my domain, so I avoid discussing it.
    • She is an expert in the domain of medieval history.
    • The company's main domain is software development.
  2. A set of websites on the internet that share a common name, such as .com, .org, or a unique address like example.com.
    • Many businesses register their domain name before launching.
    • The website's domain is easy to remember.
    • I bought a new domain for my blog last week.
  3. In mathematics, the set of all possible input values for a function.
    • To solve the problem, first find the domain of the equation.
    • The domain of this function includes all real numbers except zero.
    • The teacher explained that the domain is the set of x-values.
  4. A territory or area controlled by a ruler, government, or organization.
    • The national park is part of the public domain.
    • The empire's domain stretched across three continents.
    • The king expanded his domain by conquering neighboring lands.