What does tumour mean?
A tumour is an abnormal growth of cells that can occur in almost any part of the body. In medical usage, a tumour may be benign, meaning that it does not spread into nearby tissues or become cancerous, or malignant, meaning that it can invade surrounding tissue or spread to other parts of the body. The word is also used more broadly for an unusual lump or swelling, although the medical sense is by far the most important. “Cancer” is not an exact synonym for “tumour,” because many tumours are benign and many malignant tumours are not cancers. In ordinary discussion, the term carries a serious and often worrying association because of its close connection with malignant disease, but its meaning is technical rather than inherently negative. It is normally spelled tumour in British English and tumor in American English.
nounAn abnormal growth of cells in the body, which may be benign and harmless or malignant and cancerous. The term is used in medicine and also in general contexts for an unusual lump or swelling.
- An abnormal growth of cells in the body, either benign or malignant.
"The scan revealed a small benign tumour that required no treatment."
"Doctors removed the tumour during a routine operation."
"The report describes the findings as consistent with a slow-growing brain tumour."
The standard plural is tumours in British English; the American form is tumors.
"Several tumours were identified during the scan."
Tumour traces its history to a word for swelling, so its name preserves the basic physical fact of what a tumour is.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tumour come from?
The word entered English in the early 17th century through Latin tumor, meaning “a swelling,” and is ultimately connected with an Indo-European root associated with swelling. Related English words include tumefaction, tumescent, and tumidity, while tumor is the modern American spelling of the same word.
Related word forms
How tumour is actually used
The word is formal and especially common in medical contexts, though it is also understood by general audiences. It should not be used as a general synonym for cancer: a tumour can be benign, while cancer specifically refers to a malignant disease.
Easily confused with tumour
Tumor and tumour have the same meaning; tumour is the standard British spelling, while tumor is the standard American spelling.