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
Mancini then missed the 2020 season after surgery to remove a malignant tumor from his colon.
—
Los Angeles Times, 4 Feb. 2026
Each character has been leveled by life in some way, resembling the Wayne Thiebaud model on the book’s cover — flattened by misogyny or malignant passive aggression or betrayal.
—New York Times, 3 Feb. 2026
The dogs learn how to identify the cancer by smelling three boxes, with one containing a sample of malignant blood.
—Stephanie Stahl, CBS News, 30 Jan. 2026
And interferon-gamma is used against chronic granulomatous disease and a bone disease known as severe malignant osteopetrosis.
—Bruce Y. Lee, Forbes.com, 24 Jan. 2026
See All Example Sentences for malignant
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Los Angeles Times, 4 Feb. 2026
Each character has been leveled by life in some way, resembling the Wayne Thiebaud model on the book’s cover — flattened by misogyny or malignant passive aggression or betrayal.
—New York Times, 3 Feb. 2026
The dogs learn how to identify the cancer by smelling three boxes, with one containing a sample of malignant blood.
—Stephanie Stahl, CBS News, 30 Jan. 2026
And interferon-gamma is used against chronic granulomatous disease and a bone disease known as severe malignant osteopetrosis.
—Bruce Y. Lee, Forbes.com, 24 Jan. 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 10 Feb. 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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