poly·mor·pho·nuclear I. \|pälē|mȯrfə, -lə̇|m-+\adjective Etymology:polymorphous + nuclear 1.of a leukocyte: having the nucleus complexly lobed 2.: being a neutrophil or other leukocyte of typical mature form with distinctly lobed nucleus II. noun (-s) : a polymorphonuclear leukocyte