Where does “пятнадцатилетие” come from?

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

пятнадцатилетие (Russian): fifteen-year period

Definitions

  1. fifteen-year period

Ancestry of “пятнадцатилетие”, step by step

пятнадцатилетие traces back through two separate lines of ancestry.

via Russian пятна́дцать

StepLanguageWordMeaning
1Russianпятна́дцатьfifteen (15)
2Russianпятьfive; second-person singular imperative...
3Old Church Slavonicпѧтьfive
4Proto-Slavicpętьfive
5Proto-Indo-Europeanpénkʷefive

via Russian ле́то

StepLanguageWordMeaning
1Russianле́тоyear; summer, year
2Old East Slavicлѣтоtime
3Proto-Slaviclětosummer; year
4Proto-Indo-Europeanleh₁tóm
Every word from Proto-Indo-European pénkʷeEvery word from Proto-Slavic pętьEvery word from Old Church Slavonic пѧть