malignant

adjective

ma·​lig·​nant mə-ˈlig-nənt How to pronounce malignant (audio)
Synonyms of malignant
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 of malignant

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Examples of malignant in a Sentence

a highly malignant form of cancer a powerful and malignant influence
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Experts say the nodule could be benign or malignant and that prompt evaluation is important. — ABC News, 12 Oct. 2026 Claire underwent radiation and chemotherapy treatments to kill the malignant cells in his body, but the cancer returned again in 2017. — Los Angeles Times, 6 Oct. 2026 An analysis of 1,000 tissue samples representing 11 major organs in just over 400 male donors has now delivered a clear map and expression profile of missing Y chromosomes in typical, pre-cancerous, and malignant tumors. — Mike McRae 20, New Atlas, 21 Sep. 2026 The analysis also revealed significant stroke risk elevations for adults diagnosed with bladder, stomach, and liver cancers, as well as myeloid leukemia and malignant brain and nervous system tumors. — Tom Gavin, EverydayHealth.com, 9 Sep. 2026 See All Example Sentences for malignant

Word History

Etymology

Late Latin malignant-, malignans, present participle of malignari

First Known Use

1542, in the meaning defined at sense 2c

Time Traveler
The first known use of malignant was in 1542

Phrases Containing malignant

Rhymes for malignant

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Browse Nearby Words

malignancy
malignant
malignant lymphoma
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Cite this Entry

“Malignant.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/malignant. Accessed 14 Oct. 2026.

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Kids Definition

malignant

adjective
ma·​lig·​nant mə-ˈlig-nənt How to pronounce malignant (audio)
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 How to pronounce malignant (audio)
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
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