| 1 | Welsh | cywir | correct, true, real, genuine; sincere, honest,... |
| 2 | Middle Welsh | kywir | — |
| 3 | Proto-Brythonic | köwir | true, genuine, loyal, honest, correct |
| 4 | Proto-Celtic | kowīros | true, sincere, right, just, fair, honest, proper |
| 5 | Proto-Celtic | kom | with, co- |
| 6 | Proto-Indo-European | ḱóm | beside, near, by, with |
| 7 | Proto-Indo-European | ḱe | Deictic particle, here; Post-positional... |
| 8 | Middle English | kyt | — |
| 9 | German | kitt | — |
| 10 | Old High German | kuti | — |
| 11 | Proto-West Germanic | kwidu | gum, resin |
| 12 | Proto-Germanic | kweduz | resin |
| 13 | Proto-Indo-European | gʷet- | resin, gum; to say, speak |
| 14 | Proto-Indo-European | gū- | to bend; curve; arch; vault; to bow, bend, arch,... |