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

Doctors often monitor slow-moving tumors that are neither spreading nor causing symptoms, sparing patients unnecessary surgery or radiation. — Hanna Wickes, Charlotte Observer, 10 Aug. 2026

Three other tumor types showed fewer metastatic events but were not significant. — Jesse M. Pines, Forbes.com, 10 Aug. 2026

Radiopharmaceuticals are an emerging type of treatment designed to shoot radioactive isotopes directly at tumor cells. — Allison Deangelis, STAT, 10 Aug. 2026

In November 2024, Buckingham Palace announced that Beth had died after being diagnosed with an untreatable tumor. — Audrey Schmidt, PEOPLE, 9 Aug. 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