Where does “ptaszysko” come from?

ptaszysko (Polish) comes from Polish Ptak, from Old Polish ptak, from Proto-Slavic pъtakъ, from Proto-Slavic pъta, from Proto-Indo-European peth₂- — to spread out; to fly.

Ancestry of “ptaszysko”, step by step

Step	Language	Word	Meaning
1	Polish	Ptak	bird
2	Old Polish	ptak	bird
3	Proto-Slavic	pъtakъ	bird
4	Proto-Slavic	pъta	bird
5	Proto-Indo-European	peth₂-	to spread out; to fly

Every word from Proto-Indo-European peth₂- →Every word from Proto-Slavic pъta →Every word from Proto-Slavic pъtakъ →