| 1 | Middle English | tumour | tumour; The growth of tumours or boils |
| 2 | Old French | tumour | tumor |
| 3 | Latin | tumor | The state of being swollen; A swelling, tumor;... |
| 4 | Latin | -or | used to form a third-declension masculine... |
| 5 | Proto-Italic | -ōs | Creates masculine action nouns or result nouns... |
| 6 | Proto-Indo-European | -ōs | Creates masculine and feminine action nouns or... |
| 7 | Proto-Indo-European | -oss | — |
| 8 | Proto-Indo-European | -os | Creates action nouns or result nouns from verbs;... |