Where does “pikinen” come from?

pikinen (Finnish) comes from Finnish piki, from Old Swedish bik, from Middle Low German pik, from Old Saxon pik, from Proto-West Germanic *pik, from Latin pix, from Proto-Indo-European pik-, from Proto-Indo-European pi- — sap, juice.

pikinen (Finnish): pitchy of, pertaining to, or resembling pitch; filled or covered with pitch