Where does “uspać” come from?

uspać (Polish) comes from Polish spać, from Proto-Slavic sъpati, from Proto-Indo-European swep- — to sleep.

Ancestry of “uspać”, step by step

StepLanguageWordMeaning
1Polishspaćto sleep; to rest in state of reduced...
2Proto-Slavicsъpatito sleep
3Proto-Indo-Europeanswep-to sleep
Every word from Proto-Indo-European swep- →Every word from Proto-Slavic sъpati →Every word from Polish spać →
uspać — Etymology, Origin & Word History | Etymology Explorer