Where does “пятидесятилетний” come from?

пятидесятилетний (Russian) comes from Russian пятьдесят, from Russian де́сять, from Old Church Slavonic десѧть, from Proto-Slavic desętь, from Proto-Balto-Slavic *déśimt, from Proto-Indo-European déḱm̥t — ten.

пятидесятилетний (Russian): fifty-year

Definitions

  1. fifty-year

Ancestry of “пятидесятилетний”, step by step

пятидесятилетний traces back through two separate lines of ancestry.

via Russian пятьдесят

StepLanguageWordMeaning
1Russianпятьдесятfifty
2Russianде́сятьten
3Old Church Slavonicдесѧтьten
4Proto-Slavicdesętьten
5Proto-Balto-Slavic*déśimtten
6Proto-Indo-Europeandéḱm̥tten

via Russian ле́то

StepLanguageWordMeaning
1Russianле́тоyear; summer, year
2Old East Slavicлѣтоtime
3Proto-Slaviclětosummer; year
4Proto-Indo-Europeanleh₁tóm—
Every word from Proto-Indo-European déḱm̥t →Every word from Proto-Balto-Slavic *déśimt →Every word from Proto-Slavic desętь →