Where does “käpälikkö” come from?

käpälikkö (Finnish) comes from Finnish -ikko, from Proto-Finnic -ikko, from Proto-Finnic -i- — Plural number marker in other cases than the nominative (and optionally the genitive).

käpälikkö (Finnish): looped square, Saint John's Arms, Saint Hannes cross, Gorgon loop decorative symbol consisting of a square with outward pointing loops at its corners

Definitions

looped square, Saint John's Arms, Saint Hannes cross, Gorgon loop decorative symbol consisting of a square with outward pointing loops at its corners

Ancestry of “käpälikkö”, step by step

Step	Language	Word	Meaning
1	Finnish	-ikko	Forms nouns for groups of a particular number,...
2	Proto-Finnic	-ikko	Forms nouns indicating a group of things
3	Proto-Finnic	-i-	Plural number marker in other cases than the nominative (and optionally the genitive)

Every word from Proto-Finnic -i- →Every word from Finnish -ikko →Every word from Proto-Finnic -ikko →