What does tumor mean?
A tumor is an abnormal mass of tissue produced by the growth and multiplication of cells. It may be benign, meaning that it does not spread or become cancerous, or malignant, meaning that it can invade nearby tissue and spread to other parts of the body. The word can also be used more broadly for a lump or swelling, but its usual medical sense refers to an abnormal cellular growth. Doctors distinguish tumors by their appearance, location, behavior, and the results of laboratory tests. “Tumor” is the standard spelling in American English, while British English generally uses “tumour.” Although people sometimes use the word as a synonym for cancer, not all tumors are malignant, so precise medical language carefully separates benign and malignant growths.
nounA mass of tissue produced by abnormal growth of cells, which may be benign or malignant. The word can also refer more generally to a swelling or lump in the body.
- An abnormal mass of tissue formed by the growth and multiplication of cells, which may be harmless or cancerous.
- A swelling or lump in the body, especially one caused by inflammation or abnormal tissue growth.
"The scan revealed a benign tumor that required no treatment."
"An early-stage tumor was removed before it spread to nearby tissue."
"The doctor explained that the tumor was benign and not a sign of cancer."
The standard plural adds -s; British English generally uses tumours.
"Several tumors were detected during the screening."
A tumor is named for what it does: it makes tissue swell, reflecting its Latin roots in the language of swelling and enlargement.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tumor come from?
The word comes from Latin tumor, meaning “a swelling” or “tumor,” and is related to the Latin verb tumere, “to swell.” English borrowed the word in the early 17th century for swellings and abnormal growths in the body. Its relatives include tumefaction, tumescent, tumorous, and tumorigenic, all reflecting the same Latin root concerned with swelling or the formation of masses.
Related word forms
How tumor is actually used
Tumor is primarily a medical term and is usually counted as a noun, though it is often modified by words such as benign, malignant, primary, and metastatic. In American English, tumor is the standard spelling; British English generally uses tumour. The term does not by itself mean cancer, since many tumors are benign.
Easily confused with tumor
Tumour is the standard British English spelling of tumor; both words have the same meaning.