Where does “[[strnadl]], [[strznadl]]” come from?

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

Ancestry of “[[strnadl]], [[strznadl]]”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	strьnadъ	—

[[strnadl]], [[strznadl]] — Etymology, Origin & Word History | Etymology Explorer