Where does “三十日” come from?

三十日 (Japanese) comes from Japanese 日, from Old Japanese 日, from Proto-Japonic *pi — day, sun.

三十日 (Japanese): the thirtieth day of a month

Definitions

  1. the thirtieth day of a month

Ancestry of “三十日”, step by step

三十日 traces back through two separate lines of ancestry.

via Japanese 日

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

via Japanese 三十

StepLanguageWordMeaning
1Japanese三十thirty; thirty years of age
2Japanese三three, 3; third; three
3Middle Chineseさん—
Every word from Proto-Japonic *pi →Every word from Old Japanese 日 →Every word from Japanese 日 →