Reconstruction:Proto-Slavic/brězgъ

Probably from Proto-Indo-European *bʰreHg- (“to rot, to stink”) + *-zgъ. Possibly akin to Norwegian brisk (“bitter”), English brisk (“fizzy”).

Parallel to this term, there are also Proto-Slavic *brěčь (“resin, pitch”), Proto-Slavic *briskъ (“drop, shred, slice”), Proto-Slavic *břuxъ (“blister”). It is safe to assume all of these terms ultimately represent various resultant extensions of Proto-Indo-European *bʰer- (“to process, to carry out”).

*brězgъ m

1. tar taste

• *braga (“must, yeast”)
• *brězgati (“to burst, to decompose”).

• East Slavic:
  • Ukrainian: бреск (bresk, “bitterness”) (dialectal)
• West Slavic:
  • Czech: břesk
  • Polish: brzazg

• Trubachyov, Oleg, editor (1976), “*brězgъ I”, in Этимологический словарь славянских языков [Etymological dictionary of Slavic languages] (in Russian), numbers 3 (*bratrьcь – *cьrky), Moscow: Nauka, page 18

From Proto-Balto-Slavic *brēˀsgas, from Proto-Indo-European *bʰreh₁ǵ- (“to brighten”) + *-zgъ. Cognate with Lithuanian brė́kšta (“dawn”).

Parallel to Proto-Slavic *brěskъ (“bloom, shine”).

*brězgъ m^[1]

1. dawn, daybreak

• East Slavic:
  • Old East Slavic: брѣзгъ (brězgŭ)
    • Russian: брезг (brezg) (colloquial, dialectal)
      • ⇒ Russian: бре́зжить (brézžitʹ)
• South Slavic:
  • ⇒ Old Church Slavonic:

    Old Cyrillic script: пробрѣзгъ (probrězgŭ)

    Glagolitic script: ⱂⱁⰱⱃⱑⰸⰳⱏ (pobrězgŭ)

• West Slavic:
  • Old Czech: břězk
    • Early Modern Czech: břesk
      • Czech: rozbřesk
  • Old Polish: brzazg
    • Polish: brzask

• Vasmer, Max (1964–1973) “брезг”, in Oleg Trubachyov, transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language] (in Russian), Moscow: Progress
• Trubachyov, Oleg, editor (1976), “*brězgъ II”, in Этимологический словарь славянских языков [Etymological dictionary of Slavic languages] (in Russian), numbers 3 (*bratrьcь – *cьrky), Moscow: Nauka, page 19