Entry 1 sense Webster, 1913 Neoplasm /(nē"ō̇*plăz'm)/ · Ne·o·plasm · IPA /ˈniːoʊˌplæzəm/ 01 n. A new formation or tissue, the product of morbid action. 1. A new formation or tissue, the product of morbid action.(Physiol. & Med.)