malignant
adjective
ma·lig·nant
mə-ˈlig-nənt 
1
: tending to produce death or deterioration
malignant malaria
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
Examples of malignant in a Sentence
a highly malignant form of cancer
a powerful and malignant influence
Recent Examples on the Web
About half of mammary tumors found in dogs are benign, and of those that are malignant, most can be treated successfully with surgery if caught early enough.
—
Samantha Agate, Kansas City Star, 28 Apr. 2026
Half of the mammary tumors found in dogs are benign, and of the malignant half, most can be treated successfully with surgery if caught early enough, the veterinary group notes.
—Samantha Agate, Miami Herald, 28 Apr. 2026
That one is on Stan Bowman, as was the decision to stick with Stuart Skinner and Calvin Pickard for the start of the 2025-26 season despite Skinner’s malignant inconsistency and Pickard’s career-backup resume.
—Sean Gentille, New York Times, 26 Apr. 2026
Giant cell tumors are typically non-cancerous, with only 4% of the tumors becoming malignant cancers, according to Cleveland Clinic.
—Staff Author, PEOPLE, 25 Apr. 2026
See All Example Sentences for malignant
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Samantha Agate, Kansas City Star, 28 Apr. 2026
Half of the mammary tumors found in dogs are benign, and of the malignant half, most can be treated successfully with surgery if caught early enough, the veterinary group notes.
—Samantha Agate, Miami Herald, 28 Apr. 2026
That one is on Stan Bowman, as was the decision to stick with Stuart Skinner and Calvin Pickard for the start of the 2025-26 season despite Skinner’s malignant inconsistency and Pickard’s career-backup resume.
—Sean Gentille, New York Times, 26 Apr. 2026
Giant cell tumors are typically non-cancerous, with only 4% of the tumors becoming malignant cancers, according to Cleveland Clinic.
—Staff Author, PEOPLE, 25 Apr. 2026
See All Example Sentences for malignant
Cite this Entry
“Malignant.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/malignant. Accessed 1 May. 2026.
Copy CitationKids Definition
malignant
adjective
ma·lig·nant
mə-ˈlig-nənt
1
: evil in influence or effect : injurious
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
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