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
Complications also arose for Alexis just a few years after her tumor was removed when her leg was amputated after her internal prosthetic leg failed.
—Julie Gallant, San Diego Union-Tribune, 19 Aug. 2025
For patients under 19, these same medications can be prescribed for other medical reasons, such as post-chemotherapy needs, tumor removal surgery or to treat precocious puberty (when a child goes through puberty too early).
—Charlotte Observer, 13 Aug. 2025
The grape-sized, Stage 4 tumor on his brain stem made his movements and memories shaky.
—Yuki Noguchi, NPR, 13 Aug. 2025
And the result is more tumors are being caught in the early stages when the chances of survival are much higher — around 91%.
—Lisa Jarvis, Twin Cities, 12 Aug. 2025
See All Example Sentences for tumor
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Julie Gallant, San Diego Union-Tribune, 19 Aug. 2025
For patients under 19, these same medications can be prescribed for other medical reasons, such as post-chemotherapy needs, tumor removal surgery or to treat precocious puberty (when a child goes through puberty too early).
—Charlotte Observer, 13 Aug. 2025
The grape-sized, Stage 4 tumor on his brain stem made his movements and memories shaky.
—Yuki Noguchi, NPR, 13 Aug. 2025
And the result is more tumors are being caught in the early stages when the chances of survival are much higher — around 91%.
—Lisa Jarvis, Twin Cities, 12 Aug. 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 3 Sep. 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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