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
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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
Etymology
Origin of malignant
First recorded in 1535–45; from Late Latin malignant-, stem of malignāns, present participle of malignāre “to act maliciously”; see malign, -ant
Explanation
For something that's very harmful, especially a tumor that's cancerous, use the term malignant. Malignant and its opposite benign are medical terms used to describe a tumor or growth as either cancerous or not respectively. The gn part of both words comes from the Latin word for born, but the word root mal means "evil," while bene means "kind." A malignant tumor grows uncontrollably and spreads to other parts of the body. Less commonly, malignant can also be used to mean "evil or malicious," like when someone has a malignant imagination.
Vocabulary lists containing malignant
Take the Bad with the Good: Bene and Mal
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"The Odyssey" by Homer, Books 1–7
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Beowulf
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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.
Aging HSCs are also linked to clonal hematopoiesis, an asymptomatic condition considered a premalignant state that raises the risk of blood cancers and inflammatory diseases.
From Science Daily • May 12, 2026
Overall, colorectal cancer is on the decline, largely because more people over 50 are being screened by colonoscopy, which can prevent cancer by detecting and removing premalignant polyps.
From Washington Post • Mar. 1, 2023
The evolutionary reason for this activity may be to provoke the immune system to attack patches of premalignant and malignant cells.
From New York Times • Nov. 21, 2011
For instance, drugs that mimic the action of a normal p53 gene could conceivably cause cancers to revert to a premalignant phase.
From Time Magazine Archive
Tests such as sigmoidoscopy and colonoscopy can find premalignant polyps.
From Washington Post
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.
