Where does “mainosjulkaisu” come from?

mainosjulkaisu (Finnish) comes from Finnish julkaisu, from Finnish julkaista, from Finnish julki, from Finnish -i, from Proto-Uralic -j — oblique plural.

mainosjulkaisu (Finnish): advertising publication

Definitions

advertising publication

Ancestry of “mainosjulkaisu”, step by step

mainosjulkaisu traces back through two separate lines of ancestry.

via Finnish julkaisu

Step	Language	Word	Meaning
1	Finnish	julkaisu	publication; publishing; release
2	Finnish	julkaista	To publish
3	Finnish	julki	public, known, to the daylight, to the open;...
4	Finnish	-i	A nominal suffix used in eg. ukko → ukki; Used...
5	Proto-Uralic	-j	oblique plural

via Finnish mainos

Step	Language	Word	Meaning
1	Finnish	mainos	advertisement
2	Finnish	mainoa	—

Every word from Proto-Uralic -j →Every word from Finnish -i →Every word from Finnish julki →