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

After a biopsy revealed a tumor that thankfully hadn't spread, Pickens elected to have a radical prostatectomy to remove it. —Mekishana Pierre, Entertainment Weekly, 17 Nov. 2025

This can help enable fast-growing tumors like glioblastoma, an aggressive form of brain cancer that resists treatment and almost always comes back. —Khloe Quill, FOXNews.com, 17 Nov. 2025

Regular CT scans and blood tests watch for any new tumor growth. —Kerry Breen, CBS News, 15 Nov. 2025

In 2010, an X-ray scan revealed a rare type of tumor growing in Coppola’s chest. —Naomi Fry, New Yorker, 15 Nov. 2025

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