Where does “järkeenkäyvä” come from?

järkeenkäyvä (Finnish) comes from Finnish käyvä, from Finnish -sti, from Proto-Finnic -stik — Forms adverbs of manner from adjectives.

Ancestry of “järkeenkäyvä”, step by step

järkeenkäyvä traces back through two separate lines of ancestry.

via Finnish käyvä

StepLanguageWordMeaning
1FinnishkäyväPresent active participle of käydä
2Finnish-stiForms adverbs describing how many times something...
3Proto-Finnic-stikForms adverbs of manner from adjectives

via Finnish järki

StepLanguageWordMeaning
1Finnishjärkireason; sense
2Proto-Finnicjärkirow; order, condition
Every word from Proto-Finnic -stik