Where does “নদ” come from?

নদ (Bengali) comes from Sanskrit नद, from Proto-Indo-Iranian *nadás, from Proto-Indo-European ned- — to be wet; wet; to tie together.

Ancestry of “নদ”, step by step

StepLanguageWordMeaning
1Sanskritनदriver
2Proto-Indo-Iranian*nadás—
3Proto-Indo-Europeanned-to be wet; wet; to tie together
Every word from Proto-Indo-European ned- →Every word from Proto-Indo-Iranian *nadás →Every word from Sanskrit नद →