Domain

  1. A field or sphere of activity, influence or expertise. (from https://en.wiktionary.org/wiki/domain)
  2. A delineated portion or sphere of reality corresponding to a scientific discipline (such as cell biology or electron microscopy), or to an area of knowledge or interest such as the Great War or stamp collecting. (from Building Ontologies with Basic Formal Ontology, R. Arp, B. Smith, A. Spear)