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. White
Examples of tumor in a Sentence
the scan showed a small tumor in her abdomen
Recent Examples on the Web
The imaging can show how thick the endometrium (lining of the uterus) is and whether there are cysts, uterine or ovarian tumors, or anything else of concern.
—Sarah Bence, Health, 7 Feb. 2025
Female firefighters were 254% times more likely to develop brain tumors and have a high risk of thyroid cancer and melanoma.
—Uma Raja, Sun Sentinel, 6 Feb. 2025
This occurs when a typically noncancerous pituitary tumor produces too much cortisol in the body.1
Both Cushing disease and Cushing syndrome are relatively rare, with the disease showing up in about 10 to 15 cases per million people and the syndrome in 40 to 70 per million.
—Gillian Mohney, Verywell Health, 6 Feb. 2025
As per Healthline, patches or ulcers may indicate abnormal cell growth, which can develop into malignant tumors.
—Dan Perry, Newsweek, 31 Jan. 2025
See all Example Sentences for tumor 
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Sarah Bence, Health, 7 Feb. 2025
Female firefighters were 254% times more likely to develop brain tumors and have a high risk of thyroid cancer and melanoma.
—Uma Raja, Sun Sentinel, 6 Feb. 2025
This occurs when a typically noncancerous pituitary tumor produces too much cortisol in the body.1
Both Cushing disease and Cushing syndrome are relatively rare, with the disease showing up in about 10 to 15 cases per million people and the syndrome in 40 to 70 per million.
—Gillian Mohney, Verywell Health, 6 Feb. 2025
As per Healthline, patches or ulcers may indicate abnormal cell growth, which can develop into malignant tumors.
—Dan Perry, Newsweek, 31 Jan. 2025
See all Example Sentences for tumor
Dictionary Entries Near tumor
Cite this Entry
“Tumor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tumor. Accessed 21 Feb. 2025.
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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