Definition of “domain”

noun

1. land governed by a ruler or government
2. land owned by one person or family
3. a field or scope of knowledge or activity
4. a region having specific characteristics or containing certain types of plants or animals
5. Australian New Zealand a park or recreation reserve maintained by a public authority, often the government
6. law the absolute ownership and right to dispose of land See also demesne , eminent domain
7. mathematics 
   1. the set of values of the independent variable of a function for which the functional value exists  ⇒ the domain of sin x is all real numbers Compare range (sense 8a)
   2. any open set containing at least one point
8. logic another term for universe of discourse  ⇒ domain of quantification 
9. philosophy range of significance (esp in the phrase domain of definition)
10. magnetic domainphysics one of the regions in a ferromagnetic solid in which all the atoms have their magnetic moments aligned in the same direction
11. computing a group of computers, functioning and administered as a unit, that are identified by sharing the same domain name on the internet
12. superkingdombiology the highest level of classification of living organisms. Three domains are recognized: the highest level of classification of living organisms. Three domains are recognized: Archaea  (see archaean), the highest level of classification of living organisms. Three domains are recognized: (see ), Bacteria  (see bacteria), and the highest level of classification of living organisms. Three domains are recognized: (see ), (see ), and Eukarya (see eukaryote)
13. biochemistry a structurally compact portion of a protein molecule