Where does “бог знает какой” come from?

бог знает какой (Russian) comes from Russian зна́ть, from Old Russian знати, from Proto-Slavic znati, from Proto-Balto-Slavic źnōˀtei, from Proto-Indo-European ǵnéh₃t, from Proto-Indo-European ǵneh₃- — to know.

бог знает какой (Russian): any kind of; God knows what kind of; Lord knows what kind of; some kind of

Definitions

  1. any kind of; God knows what kind of; Lord knows what kind of; some kind of

Ancestry of “бог знает какой”, step by step

бог знает какой traces back through 3 separate lines of ancestry.

via Russian зна́ть

StepLanguageWordMeaning
1Russianзна́тьto know: to be familiar with or accustomed to a person, place, or thing
2Old Russianзнати
3Proto-Slavicznatito know
4Proto-Balto-Slavicźnōˀteito know
5Proto-Indo-Europeanǵnéh₃tto know; to get to know, to meet
6Proto-Indo-Europeanǵneh₃-to know

via Russian како́й

StepLanguageWordMeaning
1Russianкако́йwhat, which
2Old East Slavicкакъwhat, which
3Proto-Slavickakъof what/which kind
4Proto-Balto-Slavic*kōkos

via Russian Бог

StepLanguageWordMeaning
1RussianБогGod
2Old East Slavicбогъgod
3Proto-Slavicbȍgъshare, cut, wealth, luck
Every word from Proto-Indo-European ǵneh₃-Every word from Proto-Indo-European ǵnéh₃tEvery word from Proto-Balto-Slavic źnōˀtei