General Science



  • A realm of expertise, knowledge, or activity, such as electronics.
  • Within a ferromagnetic substance, a region in which the atomic or ionic magnetic moments are aligned in the same direction. Such a domain may be used, for in-stance, to store a bit as a 1 or a 0 on a magnetic tape or disk. Also called magnetic domain, or ferromagnetic domain.
  • Within a ferroelectric substance, a region whose electric moments are aligned in the same direction.
  • In database management, all the possible values for a given attribute.
  • On the Internet, one of the one of the main registration categories, such as .com, .net, .org, .edu, .gov, or country designators, such as. de for Germany. It consists of no less than two letters, and appears at the end of a domain name, as in the .com portion of Also called top-level domain.
  • In a network, a collection of resources which are administered as a unit.

Health Economics

  • (written as Domain)
    In health economics, when not used in one of its mathematical senses, this usually refers to the attributes of a health measure.

Information & Library Science

  • noun the part of an e-mail address after the @ sign


  • noun the territory ruled by a specific government or leader

Origin & History of “domain”

Etymologically, domain means ‘land belonging to a lord’, but its resemblance to such words as dominate and dominion is somewhat adventitious. Until the 17th century it was essentially the same word as demesne: demaine or demeine ‘lord’s estate’ was the Old French equivalent of (and indeed source of) English demesne. It came ultimately from Latin dominicus ‘of a lord’, but its etymological connection with Latin dominus ‘lord’ had become somewhat obscured over the centuries. But then, around 1600, by association with Latin dominium (source of English dominion), French demaine became altered to domaine, which English borrowed as domain.