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
As the sugar circulates throughout the body, it is absorbed by cancer cells and shows tumors invisible on standard X-rays.
—Anna Giorgi, Verywell Health, 14 July 2025
After having a tumor roughly the size of a small basketball on her right ovary removed before the diagnosis, doctors then removed a smaller one on her left ovary three months later, the hospital said.
—Becca Longmire, People.com, 9 July 2025
Six months ago, two weeks before my planned starting date, a mysterious pain in my side sent me to see Doc Morris for a checkup that led to a surprise double surgery to remove both a dodgy gallbladder and a carrot-sized tumor from my lower intestines, the first serious medical crisis of my life.
—James Dodson
july 7, Literary Hub, 7 July 2025
Rhonda's mother was diagnosed with dementia; Jason's mother developed a brain tumor.
—Melonee Hurt, The Tennessean, 4 July 2025
See All Example Sentences for tumor
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Anna Giorgi, Verywell Health, 14 July 2025
After having a tumor roughly the size of a small basketball on her right ovary removed before the diagnosis, doctors then removed a smaller one on her left ovary three months later, the hospital said.
—Becca Longmire, People.com, 9 July 2025
Six months ago, two weeks before my planned starting date, a mysterious pain in my side sent me to see Doc Morris for a checkup that led to a surprise double surgery to remove both a dodgy gallbladder and a carrot-sized tumor from my lower intestines, the first serious medical crisis of my life.
—James Dodson
july 7, Literary Hub, 7 July 2025
Rhonda's mother was diagnosed with dementia; Jason's mother developed a brain tumor.
—Melonee Hurt, The Tennessean, 4 July 2025
See All Example Sentences for tumor
Cite this Entry
“Tumor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tumor. Accessed 20 Jul. 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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