Where does “ngoài trời” come from?

ngoài trời (Vietnamese) comes from Vietnamese trời, from Proto-Vietic b-ləːj, from Proto-Mon-Khmer briiʔ — sky; rain; forest.

ngoài trời (Vietnamese): outdoor; open-air

Definitions

  1. outdoor; open-air

Ancestry of “ngoài trời”, step by step

ngoài trời traces back through two separate lines of ancestry.

via Vietnamese trời

StepLanguageWordMeaning
1Vietnamesetrờithe sky; weather; a generic deification of the...
2Proto-Vieticb-ləːjsky
3Proto-Mon-Khmerbriiʔsky; rain; forest

via Vietnamese ngoài

StepLanguageWordMeaning
1Vietnamesengoàioutside, exterior; outside, out of; in, inside
2Middle Chinese外—
Every word from Proto-Mon-Khmer briiʔ →Every word from Proto-Vietic b-ləːj →Every word from Vietnamese trời →