Where does “Trznadel” come from?

Trznadel (Polish) comes from Old Polish [[strnadl]], [[strznadl]], from Proto-Slavic strьnadъ.

Ancestry of “Trznadel”, step by step

Step	Language	Word	Meaning
1	Old Polish	[[strnadl]], [[strznadl]]	—
2	Proto-Slavic	strьnadъ	—