Where does “আঢ়” come from?

আঢ় (Bengali) comes from Sanskrit आषाढ, from Sanskrit अषाढ, from Proto-Indo-Aryan *asaẓḍʰas.

Ancestry of “আঢ়”, step by step

StepLanguageWordMeaning
1Sanskritआषाढthe fourth month of the Hindu lunar calendar (in which the full moon is near the constellation अषाढा)
2Sanskritअषाढinvincible, unconquerable
3Proto-Indo-Aryan*asaẓḍʰas—
Every word from Proto-Indo-Aryan *asaẓḍʰas →Every word from Sanskrit अषाढ →Every word from Sanskrit आषाढ →