Where does “тоску” come from?

тоску (Tuvan) comes from Tuvan тос, from Proto-Turkic tokuŕ — nine.

тоску (Tuvan): ninth

Definitions

  1. ninth

Ancestry of “тоску”, step by step

тоску traces back through two separate lines of ancestry.

via Tuvan тос

StepLanguageWordMeaning
1Tuvanтосnine
2Proto-Turkictokuŕnine

via Tuvan ку

StepLanguageWordMeaning
1Tuvanку
Every word from Proto-Turkic tokuŕEvery word from Tuvan тос