| 1 | English | fervour | An intense, heated emotion; passion, ardour; A... |
| 2 | Old French | fervor | — |
| 3 | Latin | fervor | boiling heat; fermenting; ardour, passion, fury |
| 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;... |