Where does “однокашник” come from?

однокашник (Russian) comes 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.

однокашник (Russian): schoolmate, college mate, fellow student

Definitions

  1. schoolmate, college mate, fellow student

Ancestry of “однокашник”, step by step

StepLanguageWordMeaning
1Russianодно-uni-
2Russianоди́н—
3Old East Slavicоди́нъ—
4Proto-Slavicedìnъone
5Proto-Balto-Slavicedīˀnas—
6Proto-Balto-Slavicaiˀnasone
7Proto-Indo-Europeanóynosone; single
Every word from Proto-Indo-European óynos →Every word from Proto-Balto-Slavic aiˀnas →Every word from Proto-Balto-Slavic edīˀnas →