Where does “よ” come from?

よ (Old Japanese) comes from Japanese 夜, from Old Japanese よる, from Proto-Japonic yoru, from Proto-Japonic yo — night.

Ancestry of “よ”, step by step

StepLanguageWordMeaning
1Japanese夜night, evening
2Old Japaneseよる—
3Proto-Japonicyorunight
4Proto-Japonicyonight

Words derived from “よ”

Every word from Proto-Japonic yo →Every word from Proto-Japonic yoru →Every word from Old Japanese よる →