Where does “天文単位” come from?

天文単位 (Japanese) comes from Japanese 天文, from Old Japanese てんもん, from Middle Chinese てんもん.

天文単位 (Japanese): astronomical unit

Definitions

  1. astronomical unit

Ancestry of “天文単位”, step by step

天文単位 traces back through two separate lines of ancestry.

via Japanese 天文

StepLanguageWordMeaning
1Japanese天文astronomy
2Old Japaneseてんもん—
3Middle Chineseてんもん—

via Japanese 単位

StepLanguageWordMeaning
1Japanese単位unit of measure; unit; academic credit
2Middle Chinese單位—
Every word from Middle Chinese てんもん →Every word from Old Japanese てんもん →Every word from Japanese 天文 →