any organism having as its fundamental structural unit a cell type that contains specialized organelles in the cytoplasm, a membrane-bound nucleus enclosing genetic material organized into chromosomes, and an elaborate system of division by mitosis or meiosis, characteristic of all life forms except bacteria, blue-green algae, and other primitive microorganisms.
any member of the Eukarya, a domain of organisms having cells each with a distinct nucleus within which the genetic material is contained. Eukaryotes include protoctists, fungi, plants, and animalsCompare prokaryote
also eucaryotic, "characterized by well-defined cells (with nuclei and cell walls)," 1957, from French eucaryote (1925), from Greek eu "well" (see eu-) + karyon "nut, kernel" (see karyo-). Related: Eukaryote; eucaryote.
An organism whose cells contain a nucleus surrounded by a membrane and whose DNA is bound together by proteins (histones) into chromosomes. The cells of eukaryotes also contain an endoplasmic reticulum and numerous specialized organelles not present in prokaryotes, especially mitochondria, Golgi bodies, and lysosomes. The organelles are enclosed in a three-part membrane (called a unit membrane) consisting of a lipid layer sandwiched between two protein layers. All organisms except for bacteria and archaea are eukaryotes. Compare prokaryote.