| 1 | Old Portuguese | rosto | face |
| 2 | Latin | rōstrum | — |
| 3 | Latin | ferreorostris | having a cruel beak |
| 4 | Latin | ferreus | iron, made of iron; like or pertaining to iron;... |
| 5 | Latin | ferrum | iron; any tool made of iron; fight, clash |
| 6 | Cornish | -er | — |
| 7 | English | -er | A person or thing that does an action indicated... |
| 8 | Middle English | -er | agentive suffix; agent noun suffix |
| 9 | Old French | -er | Alternative form of -ier, verbal suffix;... |
| 10 | Latin | -āre | — |
| 11 | Proto-Italic | -āō | Forms primarily denominative verbs |
| 12 | Proto-Indo-European | -eh₂yéti | Creates iterative/ frequentative/ intensive... |
| 13 | Proto-Indo-European | -yéti | Creates intransitive, often deponent,... |
| 14 | Proto-Indo-European | yé- | — |