In biology, one of the two major groupings into which all organisms are divided. Included are all organisms, except bacteria and cyanobacteria (blue-green algae), which belong to the prokaryote grouping.
The cells of eukaryotes possess a clearly defined nucleus, bounded by a membrane, within which DNA is formed into distinct chromosomes. Eukaryotic cells also contain mitochondria, chloroplasts, and other structures (organelles) that, together with a defined nucleus, are lacking in the cells of prokaryotes.
An organism with cells characteristic of all life forms except primitive microorganisms such as bacteria; i.e. an organism with 'good' or membrane-bound nuclei in its cells; SYN. eucaryote.