Middle English word yef comes from Proto-Indo-European *yē, Proto-Indo-European *yo-, Proto-Indo-European *ō-, and later Proto-Germanic *jabai (When, if.)
| Dictionary entry | Language | Definition |
|---|---|---|
| *yē | Proto-Indo-European (ine-pro) | already |
| *yo- | Proto-Indo-European (ine-pro) | |
| *ō- | Proto-Indo-European (ine-pro) | |
| *ja | Proto-Germanic (gem-pro) | And (conjunctive particle). Thus, so. Yes (confirmation particle). |
| *jabą | Proto-Germanic (gem-pro) | |
| *jabai | Proto-Germanic (gem-pro) | When, if. |
| ġef | Old English (ang) | |
| yif | Middle English (enm) | If. |