/ˈkiNGdəm/
Noun, pl. kingdoms
1. A rank in the classification of organisms, below domain and above phylum; a taxon at that rank (e.g. the plant kingdom, the animal kingdom). (wiktionary.org)
2. A taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla (in zoology) or divisions in botany. (wikipedia.org)
3. Each of the three traditional divisions (animal, vegetable, and mineral) in which natural objects have conventionally been classified. (Google Dictionary)
4. The highest category in taxonomic classification. (Google Dictionary)
5. The highest taxonomic group into which organisms are grouped; one of five biological categories: Monera or Protoctista or Plantae or Fungi or Animalia. (wordnetweb.princeton.edu)
Word origin: Latin, regnum, pl. regna