tumour
Pluraltumours
US spellingtumor
- 1A mass of tissue in or on the body formed by cells growing abnormally, which may be benign or malignant; in older medical use, any abnormal swelling.
Surgeons at the hospital removed a benign tumour from her spinal cord.
Doctors are testing whether the drug can shrink tumours in patients with advanced bowel cancer.
UsageOften a benign tumour (non-cancerous) or a malignant tumour (cancerous), and named by place: a brain tumour.
Note
Latin tumor meant a swelling, from a verb for bulging, and the same ancient root gives English thumb. Medicine keeps some of that breadth: tumour names the lump before it names the disease, and the first questions are what kind of growth it is and whether it is benign or malignant. American English spells it tumor, as in brain tumor.
Checked 5 Nov 2026 · 4 facts
- Latin tumor meant swelling, but also had figurative meanings, including pride. fr.wiktionary.org
- Latin tumor derives from a verb meaning to bulge or swell. fr.wiktionary.org
- Tumour and thumb share an ancient root. en.wiktionary.org
- The American spelling is tumor. en.wikipedia.org
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Origin
The word came into Middle English from Old French tumour. Its source is Latin tumor, 'swelling', a noun from the verb tumeō, 'to bulge, swell', which goes back to the Proto-Indo-European root *tewh₂-, 'to swell'. English thumb is a related word.