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

There was once a mass shooter who was found to have a brain tumor. — Literary Hub, 18 Sep. 2026

The technique dates back to the 1970s, when British engineer Godfrey Hounsfield built the first clinical scanner in London, which was later used to detect a brain tumor. — New Atlas, 17 Sep. 2026

Applying the full reprogramming process to an adult organism would be dangerous because the resulting pluripotent cells could form tumors known as teratomas. — Venki Ramakrishnan, Scientific American, 15 Sep. 2026

More serious risks include pancreatitis, gallbladder disease, and kidney injury from dehydration, and both molecules carry a boxed warning for thyroid C-cell tumors. — Daniel Fusch, USA Today, 15 Sep. 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