Reconstruction:Proto-Slavic/dori

Limited to South Slavic, of uncertain origin:

• Traditionally viewed (by Mladenov, Miklošič) as a dialectal alteration of Proto-Slavic *da že (“even though”), via rhotacism of *-ž- > -r- (as in Slovene kȁr (“which, so”) < *ka že, tọ́re (“therefore”) < *to že, Serbo-Croatian jȅr (“because of”) < *je že). Doubted by Georgiev (BER).
• In view of the wider spread of the adverb in Bulgarian and Macedonian, where the referred rhotacism is not typical, perhaps inherited. Maybe a r-extension of Proto-Balto-Slavic *da (“positional/locative particle”), akin to Lithuanian dár (“yet, still”), or a fossilized instrumental case of unattested Proto-Slavic *dorь from Proto-Indo-European *dʰer- (“to perform, to undertake, to support”).

*dori

1. yet, even so, inspite of

   Synonyms: *ješče, *da že

• *dorъde (“until, while”) (adverb)

• South Slavic:
  • Bulgarian: дори́ (dorí)
  • Macedonian: дури (duri)
  • Torlakian Serbo-Croatian: дори

• Georgiev, Vladimir I., editor (1971), “дори”, in Български етимологичен речник [Bulgarian Etymological Dictionary] (in Bulgarian), volumes 1 (А – З), Sofia: Bulgarian Academy of Sciences Pubg. House, →ISBN, page 413
• “dar”, in Lietuvių kalbos etimologinio žodyno duomenų bazė [Lithuanian etymological dictionary database], 2007–2012
• Snoj, Marko (2016) “-r”, in Slovenski etimološki slovar [Slovenian Etymology Dictionary] (in Slovene), 3rd edition, https://fran.si