( BrE ) ( NAmE tu·mor ) / ˈtjuːmə(r); NAmE ˈtuː-/ noun
a mass of cells growing in or on a part of the body where they should not, usually causing medical problems :
a brain tumour
a benign / malignant (= harmless / harmful) tumour
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WORD ORIGIN
late Middle English : from Latin tumor , from tumere to swell.