/ Dictionary / Index M malignant: Meaning and Definition of Find definitions for: ma•lig•nant Pronunciation: (mu-lig'nunt), [key] — adj. disposed to cause harm, suffering, or distress deliberately; feeling or showing ill will or hatred. very dangerous or harmful in influence or effect. tending to produce death, as bubonic plague. (of a tumor) characterized by uncontrolled growth; cancerous, invasive, or metastatic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: malignant (Thesaurus) malignancy malignity Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language