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
In August 2023, doctors discovered that her months of chest pain, shortness of breath and an elevated heart rate were actually caused by tumors pressing against her trachea, heart and arteries, leading to a stage 2 Hodgkin lymphoma diagnosis.
—Tereza Shkurtaj, PEOPLE, 23 May 2026
Researchers also found that patients with tumors who had higher GLP-1 receptor levels tended to live longer overall.
—Anthony Thompson, USA Today, 23 May 2026
Throughout the second season, Watson had also been experiencing hallucinations of Sherlock brought on by a brain tumor.
—Brianna Zigler, Entertainment Weekly, 22 May 2026
The procedure is commonly used to spot gallstones, inflammation and tumors.
—Paul Sisson, San Diego Union-Tribune, 22 May 2026
See All Example Sentences for tumor
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Tereza Shkurtaj, PEOPLE, 23 May 2026
Researchers also found that patients with tumors who had higher GLP-1 receptor levels tended to live longer overall.
—Anthony Thompson, USA Today, 23 May 2026
Throughout the second season, Watson had also been experiencing hallucinations of Sherlock brought on by a brain tumor.
—Brianna Zigler, Entertainment Weekly, 22 May 2026
The procedure is commonly used to spot gallstones, inflammation and tumors.
—Paul Sisson, San Diego Union-Tribune, 22 May 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 29 May. 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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