tumor

American  

[too-mer, tyoo-] / ˈtu mər, ˈtyu- /

especially British, tumour

noun

1. a swollen part; swelling; protuberance.

2. an uncontrolled, abnormal, circumscribed growth of cells in any animal or plant tissue; neoplasm.

3. Archaic.

   1. inflated pride; haughtiness.

   2. pompous language; bombast.

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tumor Scientific  

/ to̅o̅′mər /

1. See neoplasm See Note at cancer

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tumor Cultural  

1. An abnormal mass of new tissue growth that serves no function in the body. Tumors are usually classified as benign or malignant and are often caused by cancer.

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Other Word Forms

• antitumor adjective
• antitumoral adjective
• nontumorous adjective
• tumoral adjective
• tumorlike adjective
• tumorous adjective

Etymology

Origin of tumor

First recorded in 1535–45; from Latin: “a swelling, swollen state,” equivalent to tum(ēre) “to swell” + -or noun suffix ( -or ¹ )

Example Sentences

Removal of the tumor was scheduled for two months later, so Duong went home to his family for the weekend.

From Los Angeles Times • Mar. 30, 2026

This research shows that effectiveness depends not only on whether a drug reaches a tumor, but also on how it spreads within it and inside individual cells.

From Science Daily • Mar. 27, 2026

Future studies will use animal models and larger patient groups to better understand how drug delivery, tumor structure, and lysosomal storage interact in clinical settings, including in relapsed cancers.

From Science Daily • Mar. 27, 2026

This allowed the bacteria to function as a targeted treatment, delivering the drug directly to tumor sites.

From Science Daily • Mar. 21, 2026

He didn’t look particularly sorry about my grandfather’s brain tumor.

From "Darius the Great Is Not Okay" by Adib Khorram

Related Words

• Cancer
• carcinoma
• cyst
• lump
• swelling