any of various one-celled organisms, classified in the kingdom Protista,
that are either free-living or aggregated into simple colonies and that
have diverse reproductive and nutritional modes, including the
protozoans, eukaryotic algae, and slime molds: some classification
schemes also include the fungi and the more primitive bacteria and
blue-green algae or may distribute the organisms between the kingdoms
Plantae and Animalia according to dominant characteristics.
(used with a plural verb)
Biology. a taxonomic kingdom, or in some classification schemes a
division of the kingdom Plantae, comprising all the fungus groups and
sometimes also the slime molds.