Where does “Szczyrba” come from?

Szczyrba (Polish) comes from Polish szczerba, from Proto-Slavic ščьrba, from Proto-Balto-Slavic *skirbā.

Ancestry of “Szczyrba”, step by step

Step	Language	Word	Meaning
1	Polish	szczerba	gap, dent, jag, chip, nick, notch
2	Proto-Slavic	ščьrba	—
3	Proto-Balto-Slavic	*skirbā	—