Where does “pejsek” come from?

pejsek (Czech) comes from Czech pes, from Old Church Slavonic pes, from Proto-Slavic pьsъ, from Proto-Balto-Slavic píśas.

Ancestry of “pejsek”, step by step

StepLanguageWordMeaning
1Czechpesdog; male dog; scoundrel, bad person
2Old Church Slavonicpes—
3Proto-Slavicpьsъdog
4Proto-Balto-Slavicpíśas—
Every word from Proto-Balto-Slavic píśas →Every word from Proto-Slavic pьsъ →Every word from Old Church Slavonic pes →
pejsek — Etymology, Origin & Word History | Etymology Explorer