Where does “সিদ্ধাৰ্থ” come from?

সিদ্ধাৰ্থ (Assamese) comes from Sanskrit सिद्धार्थ, from Sanskrit अर्थ, from Proto-Indo-Iranian Hártʰam, from Proto-Indo-European h₁ert-, from Proto-Indo-European h₁er- — earth.

Ancestry of “সিদ্ধাৰ্থ”, step by step

Step	Language	Word	Meaning
1	Sanskrit	सिद्धार्थ	reached a goal, accomplished an aim; successful;...
2	Sanskrit	अर्थ	aim, purpose, meaning; advantage; profit
3	Proto-Indo-Iranian	Hártʰam	affair, occurrence; object, thing; purpose
4	Proto-Indo-European	h₁ert-	earth
5	Proto-Indo-European	h₁er-	earth

Every word from Proto-Indo-European h₁er- →Every word from Proto-Indo-European h₁ert- →Every word from Proto-Indo-Iranian Hártʰam →