Where does “застынуть” come from?

застынуть (Russian) comes from Russian сты́нуть, from Proto-Slavic stydnǫti, from Proto-Balto-Slavic stūˀd-.

Ancestry of “застынуть”, step by step

StepLanguageWordMeaning
1Russianсты́нутьto wither, to shrivel, to fade, to dry up e.g. of flowers
2Proto-Slavicstydnǫtito cool
3Proto-Balto-Slavicstūˀd-—
Every word from Proto-Balto-Slavic stūˀd- →Every word from Proto-Slavic stydnǫti →Every word from Russian сты́нуть →