malignant
Americanadjective
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disposed to cause harm, suffering, or distress deliberately; feeling or showing ill will or hatred.
- Synonyms:
- malevolent, spiteful
- Antonyms:
- benign
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very dangerous or harmful in influence or effect.
- Synonyms:
- pernicious, hurtful, perilous
- Antonyms:
- benign
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Pathology.
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tending to produce death, as bubonic plague.
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(of a tumor) characterized by uncontrolled growth; cancerous, invasive, or metastatic.
- Antonyms:
- benign
-
adjective
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having or showing desire to harm others
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tending to cause great harm; injurious
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pathol (of a tumour) uncontrollable or resistant to therapy; rapidly spreading
noun
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Tending to have a destructive clinical course, as a malignant illness.
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Relating to cancer cells that are invasive and tend to metastasize. Malignant tumor cells are histologically more primitive than normal tissue.
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Compare benign
Usage
What’s the difference between malignant and benign? In a medical context, the word malignant is used to describe harmful masses or tumors that are cancerous and that grow and spread disease. The word benign is the opposite—it’s used to describe masses or tumors that are not cancerous (those that do not spread disease to other parts of the body).Both words are sometimes also used in general ways. Malignant can mean harmful or intended or intending to cause harm, while benign can mean kind, favorable, or gracious.The best clue to help remember their meanings is the prefix mal-, which means “bad” and shows up in a lot of other negative words, such as malfunction, malpractice, malicious, and maleficent.Here’s an example of malignant and benign used correctly in the same sentence.Example: She was afraid the lump was a malignant tumor, but it turned out to be a benign cyst—totally harmless.Want to learn more? Read the full breakdown of the difference between malignant and benign.
Discover More
The term is often used in a general way to denote something that is both destructive and fast growing: “The malignant growth of the suburbs is destroying the landscape.”
The term malignant is used in describing cancerous tumors (see cancer) because such growths are a threat to the health of the individual.
Other Word Forms
- malignantly adverb
- nonmalignant adjective
- nonmalignantly adverb
- semimalignant adjective
- semimalignantly adverb
- unmalignant adjective
- unmalignantly adverb
Etymology
Origin of malignant
First recorded in 1535–45; from Late Latin malignant-, stem of malignāns, present participle of malignāre “to act maliciously”; malign, -ant
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
So everything he is doing now is about legacy, and with a malignant narcissist who knows that he may not be long for this earth, the danger that comes with those realizations is acute.
From Salon • Mar. 29, 2026
In tissues that are cancerous or at risk of becoming malignant, the same molecules can stimulate tumor growth through eIF5A2.
From Science Daily • Mar. 2, 2026
“The more he stretches the truth in the name of the sale, the more desperate he becomes. Once inside our living room, however, he is far more malignant than any of that.”
From Slate • Feb. 25, 2026
Marcin, initially as malignant as Hook and as blinkered as Torvald, eventually grows as repentant and noble as Oberon in “A Midsummer Night’s Dream,” which will co-star a certain native of Toruń as Titania.
From The Wall Street Journal • Feb. 3, 2026
There was, it seemed, more reason for merriment than the deception of malignant spirits: This day the women were rowed ashore from their ships, and have taken up residence with us.
From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume II: The Kingdom on the Waves" by M.T. Anderson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
