eukaryote UK /juːˈkæɹi.əʊt/US /juˈkæɹi.oʊt/ noun1 •Any of the single-celled or multicellular organisms of the taxonomic domain Eukaryota, whose cells contain at least one distinct nucleus.It is now clear that among organisms there are two different organizational patterns of cells, which Chatton (1937) called, with singular prescience, the eucaryotic and procaryotic type. — 1962 formseukarya · eukaryotes