polymorphonuclear Syllabification: (pol·y·mor·pho·nu·cle·ar)Pronunciation: /ˌpäliˌmôrfōˈn(y)o͞oklēər/Definition of polymorphonuclear adjective Physiology (of a leukocyte) having a nucleus with several lobes and a cytoplasm that contains granules, as in an eosinophil or basophil. polymorphonuclear in other Oxford dictionaries Definition of polymorphonuclear in the British & World English dictionary