Where does “sedmdesátník” come from?
sedmdesátník (Czech) comes from Czech sedmdesát, from Czech deset, from Old Czech desět, from Proto-Slavic desętь, from Proto-Balto-Slavic *déśimt, from Proto-Indo-European déḱm̥t — ten.
sedmdesátník (Czech): septuagenarian
Ancestry of “sedmdesátník”, step by step