Where does “мозг” come from?

мозг (Bulgarian) comes from Proto-Slavic mozgъ, from Proto-Balto-Slavic masgás, from Proto-Indo-European mosgʰós — marrow; brain.

Ancestry of “мозг”, step by step

StepLanguageWordMeaning
1Proto-Slavicmozgъmarrow, brain
2Proto-Balto-Slavicmasgásmarrow; brain
3Proto-Indo-Europeanmosgʰósmarrow; brain
Every word from Proto-Indo-European mosgʰós →Every word from Proto-Balto-Slavic masgás →Every word from Proto-Slavic mozgъ →