tu ‧ mour BrE AmE British English , tumor American English /ˈtjuːmə $ ˈtuːmər/ noun [countable]
[ Date: 1400-1500 ; Language: Latin ; Origin: tumere 'to swell' ]
a mass of diseased cells in your body that have divided and increased too quickly:
a brain tumour
malignant/benign tumour (=caused by or not caused by ↑ cancer )