| 1 | English | portentous | Of momentous or ominous significance; Ominously... |
| 2 | Latin | portentōsus | — |
| 3 | Latin | portentus | indicated, pointed out; predicted, foretold |
| 4 | Latin | portendo | I indicate, point out; I predict, foretell,... |
| 5 | Latin | por- | forth, forward, further, onward |
| 6 | Proto-Italic | por- | — |
| 7 | Proto-Indo-European | per- | before, in front; first; to go through |
| 8 | Proto-Indo-European | pr̥tós | passed , crossed |