Where does “きょう” come from?

きょう (Middle Chinese) comes from Old Japanese けふ, from Old Japanese 日, from Proto-Japonic *pi — day, sun.

Ancestry of “きょう”, step by step

きょう traces back through two separate lines of ancestry.

via Old Japanese けふ

StepLanguageWordMeaning
1Old Japaneseけふtoday
2Old Japanese日the sun; sunlight, sunshine; daytime, daylight
3Proto-Japonic*piday, sun

via Middle Chinese 鏡

StepLanguageWordMeaning
1Middle Chinese鏡—

Words derived from “きょう”

Every word from Proto-Japonic *pi →Every word from Old Japanese 日 →Every word from Old Japanese けふ →