Where does “неоднократный” come from?
неоднократный (Russian) comes from Russian однокра́тный, from Russian одно-, from Russian оди́н, from Old East Slavic оди́нъ, from Proto-Slavic edìnъ, from Proto-Balto-Slavic edīˀnas, from Proto-Balto-Slavic aiˀnas, from Proto-Indo-European óynos — one; single.
Ancestry of “неоднократный”, step by step