Where does “кой” come from?
кой (Russian) comes from Old East Slavic къи, from Proto-Slavic kъjь, from Proto-Slavic -jь, from Proto-Indo-European yós, from Proto-Finnic wiša, from Proto-Indo-Iranian wišás, from Proto-Indo-European wisós — fluidity, slime, poison; poison; poison; slime;...
кой (Russian): how, which, who, what
Ancestry of “кой”, step by step
| Step | Language | Word | Meaning |
|---|
| 1 | Old East Slavic | къи | — |
| 2 | Proto-Slavic | kъjь | which |
| 3 | Proto-Slavic | -jь | Adjectival inherited from the Caland roots,... |
| 4 | Proto-Indo-European | yós | that, who, which |
| 5 | Proto-Finnic | wiša | — |
| 6 | Proto-Indo-Iranian | wišás | poison, venom |
| 7 | Proto-Indo-European | wisós | fluidity, slime, poison; poison; poison; slime;... |