Where does “piskělь” come from?

piskělь (Proto-Slavic) comes from Proto-Slavic piskati, from Proto-Balto-Slavic pīṣk-.

Ancestry of “piskělь”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	piskati	to squeak, to whistle
2	Proto-Balto-Slavic	pīṣk-	—