One of the four categories into which natural objects are usually classified: the animal k., including all animals; the plant k., including all plants; the mineral k., including all objects and substances without life; and the protista, including all single-cell organisms. [A.S. cyningdom, fr. cyning, king, + -dom, state, condition]
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king·dom 'kiŋ-dəm n
1) any of the three primary divisions into which natural objects are grouped see animal kingdom, mineral kingdom, plant kingdom
2) a major category (as Protista) in biological taxonomy that ranks above the phylum and below the domain
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king·dom (kingґdəm) [A.S. cyningdom] in the traditional classification of living organisms, the highest of the categories. A number of systems have been proposed; the most widely used lists five kingdoms: Monera, Protista, Fungi, Plantae (the plants), and Animalia (the animals). An alternative classification divides all organisms at the highest level into three domains (q.v.).Medical dictionary. 2011.