MALIGNANCY Meaning of MALIGNANCY in English ma ‧ lig ‧ nan ‧ cy /məˈlɪɡnənsi/ BrE AmE noun ( plural malignancies )1 . [countable] medical a ↑ tumour2 . [uncountable] formal a feeling of great hatred Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012