Where does “seikkailukirja” come from?

seikkailukirja (Finnish) comes from Finnish seikkailu, from Finnish seikkailla, from Finnish seikka, from Karelian šeikka.

seikkailukirja (Finnish): adventure book

Definitions

Step	Language	Word	Meaning
1	Finnish	seikkailu	adventure
2	Finnish	seikkailla	To adventure
3	Finnish	seikka	thing, matter; circumstance
4	Karelian	šeikka	—

seikkailukirja — Etymology, Origin & Word History | Etymology Explorer