malignant

adjective ma·lig·nant \mə-ˈlig-nənt\

medical : very serious and dangerous : tending or likely to grow and spread in a rapid and uncontrolled way that can cause death

: very evil

Full Definition of MALIGNANT

a obsolete : malcontent, disaffected

b : evil in nature, influence, or effect : injurious

c : passionately and relentlessly malevolent : aggressively malicious

: tending to produce death or deterioration <malignant malaria>; especially : tending to infiltrate, metastasize, and terminate fatally <a malignant tumor>

— ma·lig·nant·ly adverb

See malignant defined for English-language learners

See malignant defined for kids

Origin of MALIGNANT

Late Latin malignant-, malignans, present participle of malignari

First Known Use: circa 1545

Related to MALIGNANT

Synonyms: bad [slang], bitchy, catty, cruel, despiteful, malevolent, malicious, malign, hateful, mean, nasty, spiteful, vicious, virulent

Antonyms: benevolent, benign, benignant, loving, unmalicious

Rhymes with MALIGNANT

benignant, indignant

MALIGNANT Defined for Kids

malignant

adjective ma·lig·nant \mə-ˈlig-nənt\

Definition of MALIGNANT for Kids

: malicious

: likely to cause death : deadly

— ma·lig·nant·ly adverb

Medical Dictionary

malignant

adjective ma·lig·nant \mə-ˈlig-nənt\

Medical Definition of MALIGNANT

: tending to produce death or deterioration <malignant malaria>; especially : tending to infiltrate, metastasize, and terminate fatally <malignant tumors>—compare benign 1

: of unfavorable prognosis : not responding favorably to treatment <psychotic reactions with a malignant trend>