Where does “päähkänäkärkkäin” come from?

päähkänäkärkkäin (Ingrian) comes from Ingrian -in, from Proto-Finno-Ugric *-in, from Proto-Uralic -ma.

Ancestry of “päähkänäkärkkäin”, step by step

StepLanguageWordMeaning
1Ingrian-inForms adjectives indicating the material of which something is made; -en
2Proto-Finno-Ugric*-in—
3Proto-Uralic-ma—
Every word from Proto-Uralic -ma →Every word from Ingrian -in →Every word from Proto-Finno-Ugric *-in →