Where does “vai” come from?

vai (Translingual) comes from English vai, from Bengali ভাই, from Sauraseni Prakrit 𑀪𑀸𑀇, from Sanskrit भ्रातृ, from Proto-Indo-Aryan bʰráHtā, from Proto-Indo-Iranian bʰráHtā, from Proto-Indo-European bʰréh₂tēr — brother.

Ancestry of “vai”, step by step

StepLanguageWordMeaning
1EnglishvaiInitialism of verb animate intransitive: an...
2Bengaliভাইbrother
3Sauraseni Prakrit𑀪𑀸𑀇—
4Sanskritभ्रातृbrother; kinsman, relative; friend
5Proto-Indo-AryanbʰráHtābrother
6Proto-Indo-IranianbʰráHtābrother
7Proto-Indo-Europeanbʰréh₂tērbrother
Every word from Proto-Indo-European bʰréh₂tēr →Every word from Proto-Indo-Iranian bʰráHtā →Every word from Proto-Indo-Aryan bʰráHtā →