tumor

noun

tu·​mor ˈtü-mər 

ˈtyü-

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

tumoral

ˈtü-mə-rəl 

ˈtyü-

adjective

tumorlike

ˈtü-mər-ˌlīk 

ˈtyü-

adjective

Synonyms of tumor

• lump
• neoplasm
• cyst
• growth
• carcinoma

Examples of tumor in a Sentence

the scan showed a small tumor in her abdomen

Recent Examples on the Web

Imaging this week showed Brown has a stress reaction in his neck, which was in the same spot as his 2024 ailment that ultimately had been diagnosed as an osteoma (benign bone tumor). — Meghan Montemurro, Chicago Tribune, 27 June 2026

What Research Shows About Cancer in Dogs While there is no evidence that turkey tail shrinks tumors, the mushroom has drawn real scientific interest as a complementary therapy for serious illness. — Samantha Agate, Kansas City Star, 26 June 2026

Scientists have developed a technique to make CAR T-cell therapy — an advanced cancer treatment used for some blood cancers — safer and more effective for solid tumors. — Stephanie Stephens, USA Today, 26 June 2026

The center also cautions that a reishi extract was found to have toxic effects in leukocytes, and gastrointestinal cancer patients had higher levels of the serum tumor marker CA72-4 after taking reishi spore supplements. — Samantha Agate, Miami Herald, 26 June 2026

Word History

Etymology

Middle English tumour, from Latin tumor, from tumēre

First Known Use

15th century, in the meaning defined at sense 2

Phrases Containing tumor

• anti-tumor
• tumor load
• tumor necrosis factor
• tumor suppressor gene

Rhymes for tumor

• boomer
• humor
• humour
• plumer
• rumor
• rumour
• tumour
• antitumor
• pseudotumor
• consumer
• perfumer

Kids 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

ˈt(y)üm-(ə-)rəs

adjective

Medical Definition

tumor

noun

tu·​mor

variants or chiefly British tumour

ˈt(y)ü-mər 

: 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

-ˌlīk 

adjective