sphere, domain, area, orbit, field, arena (noun)

a particular environment or walk of life

"his social sphere is limited"; "it was a closed area of employment"; "he's out of my orbit"

domain, demesne, land (noun)

territory over which rule or control is exercised

"his domain extended into Europe"; "he made it the law of the land"

domain, domain of a function (noun)

(mathematics) the set of values of the independent variable for which a function is defined

world, domain (noun)

people in general; especially a distinctive group of people with some shared interest

"the Western world"

knowledge domain, knowledge base, domain (noun)

the content of a particular field of knowledge

domain (Noun)

A geographic area owned or controlled by a single person or organization.

domain (Noun)

A sphere of influence.

domain (Noun)

A group of related items, topics, or subjects.

domain (Noun)

The set of all possible mathematical entities (points) where a given function is defined.

domain (Noun)

An open and connected set in some topology. For example, the interval (0,1) as a subset of the real numbers.

domain (Noun)

Any DNS domain name, particularly one which has been delegated and has become representative of the delegated domain name and its subdomains

domain (Noun)

A collection of DNS or DNS-like domain names consisting of a delegated domain name and all its subdomains

domain (Noun)

A collection of information having to do with a domain, the computers named in the domain, and the network on which the computers named in the domain reside

domain (Noun)

The collection of computers identified by a domain's domain names

domain (Noun)

A small magnetized area of a bubble memory storing one bit, a bubble.

domain (Noun)

In the three-domain system, the highest rank in the classification of organisms, above kingdom; in other taxonomic systems, a similarly high rank

domain (Noun)

In the three-domain system, one of three taxa at that rank: Bacteria, Archaea, or Eukaryota.

domain (Noun)

A folded section of a protein molecule that has a discrete function

Domain

In biological taxonomy, a domain is the highest taxonomic rank of organisms in the Woese taxonomic system, higher than a kingdom. According to the three-domain system of Carl Woese, introduced in 1990, the Tree of Life consists of three domains: Archaea, Bacteria and Eukarya. The arrangement of taxa reflects the fundamental differences in the genomes.