Definition of "realm" in English

noun

1. (archaic or law and rhetoric) A territory or state, as ruled by an absolute authority, especially by a king; a kingdom.

   • 1913, Leslie Alexander Toke, Catholic Encyclopedia, "St. Dunstan", Then seeing his life was threatened he fled the realm and crossed over to Flanders, […]

2. (also figurative) A sphere of knowledge or of influence; a domain.

   • the realm of physics
   • the realm of corporate governance

3. (biology, ecology) A primary zoogeographical division of the earth's surface.

4. (virology, taxonomy) A taxonomic rank in the phylogeny of viruses, higher than kingdoms.

5. (archaic) A region or zone forming part of a cosmological system.