Where does “ৰাতি” come from?

ৰাতি (Early Assamese) comes from Sanskrit रात्रि, from Sanskrit रात्री, from Proto-Indo-Iranian HráHtriH, from Proto-Indo-European Hréh₁trih₂.

Ancestry of “ৰাতি”, step by step

StepLanguageWordMeaning
1Sanskritरात्रिnight
2Sanskritरात्रीnight
3Proto-Indo-IranianHráHtriHstillness of night
4Proto-Indo-EuropeanHréh₁trih₂—
Every word from Proto-Indo-European Hréh₁trih₂ →Every word from Proto-Indo-Iranian HráHtriH →Every word from Sanskrit रात्री →