1
: an abnormal benign or malignant new growth of tissue that possesses no physiological function and arises from uncontrolled usually rapid cellular proliferation
called also neoplasm
2
: a swollen or distended part
… houses that bulged with the tumors and warts of … ornamental architecture …—
W. A. White
W. A. WhiteExamples of tumor in a Sentence
the scan showed a small tumor in her abdomen
Recent Examples on the Web
Orringer's team has pioneered advanced tumor-visualization techniques to help patients.
—Hannah Kliger, CBS News, 5 Mar. 2026
There’s no tumor in my brain, God forbid.
—Ryan Coleman, Entertainment Weekly, 4 Mar. 2026
Instead, the bleeding was caused by hemorrhaging from a tumor − one roughly the size of a baby's head.
—Charles Trepany, USA Today, 4 Mar. 2026
Using visuals of both benign samples and tumor samples, as well as specialized equipment, the scientists identified plastic particles in 90% of the tumor samples and 70% of benign tissue samples, according to the study press release.
—Khloe Quill, FOXNews.com, 1 Mar. 2026
See All Example Sentences for tumor
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Hannah Kliger, CBS News, 5 Mar. 2026
There’s no tumor in my brain, God forbid.
—Ryan Coleman, Entertainment Weekly, 4 Mar. 2026
Instead, the bleeding was caused by hemorrhaging from a tumor − one roughly the size of a baby's head.
—Charles Trepany, USA Today, 4 Mar. 2026
Using visuals of both benign samples and tumor samples, as well as specialized equipment, the scientists identified plastic particles in 90% of the tumor samples and 70% of benign tissue samples, according to the study press release.
—Khloe Quill, FOXNews.com, 1 Mar. 2026
See All Example Sentences for tumor
Cite this Entry
“Tumor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tumor. Accessed 10 Mar. 2026.
Copy CitationKids Definition
tumor
noun
tu·mor
ˈt(y)ü-mər 
: an abnormal mass of tissue that arises from normal tissue cells and serves no useful purpose in the body
tumorous
adjective
ˈt(y)üm-(ə-)rəs
Medical Definition
tumor
noun
tu·mor
variants
or chiefly British tumour
: an abnormal benign or malignant new growth of tissue that possesses no physiological function and arises from uncontrolled usually rapid cellular proliferation see cancer sense 1, carcinoma, sarcoma
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