A superkingdom of organisms characterized by eukaryotic cells; its single-cell members are assigned to the kingdom Protoctista, and its multicellular members are assigned to the kingdoms Fungi, Plantae, and Animalia.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.