tu·​mor ˈtü-mər How to pronounce tumor (audio)
: 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

: a swollen or distended part
… houses that bulged with the tumors and warts of … ornamental architecture …W. A. White
tumoral adjective
tumorlike adjective

Examples of tumor in a Sentence

the scan showed a small tumor in her abdomen
Recent Examples on the Web In a new interview with Rolling Stone UK, the 74-year-old metal icon reveals that a tumor was discovered in one of his vertebrae during a fourth spinal surgery. Mitchell Peters, Billboard, 26 Nov. 2023 First would be eight rounds of neoadjuvant chemotherapy over about four months, before surgical extraction of the tumor. Paige Stables, Allure, 22 Nov. 2023 Eva Hesse of a brain tumor at age 34, Hannah Wilke of lymphoma at 52, Helen Chadwick of a heart attack at 42. Jessica Ferri, Los Angeles Times, 21 Nov. 2023 Because there were many critical organs near Salim’s tumor, the damage could be severe, causing loss of hearing, diminished sense of taste and smell, and brain impairment, like memory loss. T. Christian Miller, ProPublica, 7 Nov. 2023 While more studies are needed to fully understand its mechanisms, preliminary findings indicate that CBD oil may have a positive impact on tumor regression. Amber Smith, Discover Magazine, 5 Nov. 2023 New American Cancer Society guidelines will allow millions more to become eligible for regular scans that can detect tumors early enough to save lives. Linda Carroll, NBC News, 1 Nov. 2023 The victims of breast tumors are largely females, but about 0.5 to 1 percent of breast cancers affect men, for whom breast cancer is a little different. Sofia Quaglia, Discover Magazine, 31 Oct. 2023 Typically, the values will creep up on repeat testing until a tumor eventually appears on a scan. Mara Buchbinder, STAT, 29 Oct. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'tumor.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English tumour, from Latin tumor, from tumēre

First Known Use

15th century, in the meaning defined at sense 2

Time Traveler
The first known use of tumor was in the 15th century

Dictionary Entries Near tumor

Cite this Entry

“Tumor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tumor. Accessed 3 Dec. 2023.

Kids Definition


tu·​mor ˈt(y)ü-mər How to pronounce tumor (audio)
: an abnormal mass of tissue that arises from normal tissue cells and serves no useful purpose in the body

Medical Definition


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
tumorlike adjective

More from Merriam-Webster on tumor

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