Where does “pierwszoklasista” come from?

pierwszoklasista (Polish) comes from Polish pierwszy, from Old Polish pierwy, from Proto-Slavic pьrvъ, from Proto-Balto-Slavic pírˀwas, from Proto-Indo-European pr̥h₂wós — first.

pierwszoklasista (Polish): first-grader

Definitions

first-grader

Ancestry of “pierwszoklasista”, step by step

pierwszoklasista traces back through two separate lines of ancestry.

via Polish pierwszy

Step	Language	Word	Meaning
1	Polish	pierwszy	first
2	Old Polish	pierwy	first
3	Proto-Slavic	pьrvъ	first
4	Proto-Balto-Slavic	pírˀwas	—
5	Proto-Indo-European	pr̥h₂wós	first

via Polish klasa

Step	Language	Word	Meaning
1	Polish	klasa	class; classroom; grade
2	Latin	classis	any one of the five divisions into which Servius...
3	Proto-Italic	klāssis	—
4	Proto-Indo-European	kelh₁-	to call, cry, summon

Every word from Proto-Indo-European pr̥h₂wós →Every word from Proto-Balto-Slavic pírˀwas →Every word from Proto-Slavic pьrvъ →