Where does “петак” come from?

петак (Bulgarian) comes from Proto-Slavic pętъkъ, from Proto-Slavic pętъ, from Proto-Balto-Slavic penktas, from Proto-Hellenic penkʷtos, from Proto-Indo-European pénkʷe — five.

Ancestry of “петак”, step by step

StepLanguageWordMeaning
1Proto-SlavicpętъkъFriday
2Proto-Slavicpętъfifth
3Proto-Balto-Slavicpenktasfifth
4Proto-Hellenicpenkʷtos—
5Proto-Indo-Europeanpénkʷefive

Words derived from “петак”

Every word from Proto-Indo-European pénkʷe →Every word from Proto-Hellenic penkʷtos →Every word from Proto-Balto-Slavic penktas →