Where does “пятидневный” come from?

пятидневный (Russian) comes from Russian пять, from Old Church Slavonic пѧть, from Proto-Slavic pętь, from Proto-Indo-European pénkʷe — five.

пятидневный (Russian): five-day

Definitions

  1. five-day

Ancestry of “пятидневный”, step by step

пятидневный traces back through two separate lines of ancestry.

via Russian пять

StepLanguageWordMeaning
1Russianпятьfive; second-person singular imperative...
2Old Church Slavonicпѧтьfive
3Proto-Slavicpętьfive
4Proto-Indo-Europeanpénkʷefive

via Russian день

StepLanguageWordMeaning
1Russianденьday, daytime; afternoon, early evening;...
2Old East Slavicдьньday
3Proto-Slavicdь̑nьday
Every word from Proto-Indo-European pénkʷe →Every word from Proto-Slavic pętь →Every word from Old Church Slavonic пѧть →