malignant

adjective

ma·​lig·​nant mə-ˈlig-nənt 

1

: tending to produce death or deterioration

malignant malaria

especially : tending to infiltrate, metastasize, and terminate fatally

a malignant tumor

2

a

: evil in nature, influence, or effect : injurious

a powerful and malignant influence

b

: passionately and relentlessly malevolent : aggressively malicious

the malignant tongues of gossipers

c

obsolete : malcontent, disaffected

malignantly adverb

Synonyms

• malicious
• vicious
• cruel
• hateful
• nasty

Examples of malignant in a Sentence

a highly malignant form of cancer

a powerful and malignant influence

Recent Examples on the Web

Tumors growing where chronic injury has hijacked DNA repair and allowed malignant cells to escape control. —Bill Frist, Forbes.com, 18 Sep. 2025

If both sides have a problem, then one side has a much bigger and malignant problem and that is the truth. —Hannah Demissie, ABC News, 15 Sep. 2025

If both sides have a problem, one side has a much bigger and malignant problem, and that is the truth. —Amanda Castro hannah Parry shane Croucher, MSNBC Newsweek, 15 Sep. 2025

And that’s why Democrats on social media are celebrating his murder with such malignant depravity. —Howie Carr, Boston Herald, 12 Sep. 2025

Word History

Etymology

Late Latin malignant-, malignans, present participle of malignari

First Known Use

1542, in the meaning defined at sense 2c

Phrases Containing malignant

• malignant melanoma

Rhymes for malignant

• indignant
• nonmalignant
• premalignant

Kids Definition

malignant

adjective

ma·​lig·​nant mə-ˈlig-nənt 

1

: evil in influence or effect : injurious

2

: malicious sense 1

3

: tending to produce death

malignant tumors

malignantly adverb

Medical Definition

malignant

adjective

ma·​lig·​nant mə-ˈlig-nənt 

1

: tending to produce death or deterioration

malignant malaria

especially : tending to infiltrate, metastasize, and terminate fatally

malignant tumors

compare benign sense 1

2

: of unfavorable prognosis : not responding favorably to treatment

psychotic reactions with a malignant trend