Privative adjectives *ubogъ (“poor, miserable”) and *nebogъ (“poor, miserable”), as well as the later derivation *bogatъ (“rich”) prove that *bogъ was originally also an adjective meaning "earthly wealth/well-being; fortune", with a semantic shift to "dispenser of wealth/fortune" and finally "god". Semantic parallel can be drawn to Indo-Iranian languages: compare Old Persian 𐏎 (baga, “god”), Avestan 𐬠𐬀𐬖𐬀 (baγa, “god”) (but also 𐬠𐬀𐬔 (bag, “apportion”)), as well as Sanskrit epithet often applied to gods भग (bhaga, “dispenser, gracious lord, patron”), proving that Slavic noun had both abstract and concrete meanings. The same Iranian source, but via a Turkic language, also probably gave Proto-Slavic *banъ. Compare also Avar бакъ (baq̇̄, “sun”).
This convincing parallel has led some linguists (e.g. Roman Jakobson) to claim that *bogъ is an Iranian borrowing. Slavic-Iranian parallelism can be further extended to the expressions of Slavic mythology: Dažbog, Belobog and Chernobog, which suggest an existence of Iranian-type dualism in Proto-Slavic mythology.
Some connect it to Ancient Greek ἔφαγον (éphagon, “to eat, devour”) via a semantic shift "I received a share" > "I consumed" > "I ate". This would in turn all derive from the Proto-Indo-European root *bʰeh₂g- (“to distribute, divide”).
- East Slavic:
- South Slavic:
- Derksen, Rick (2008) Etymological Dictionary of the Slavic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 4), Leiden, Boston: Brill, ISBN 978 90 04 15504 6, page 50
- Trubačev O. N., editor (1975), “*bogъ”, in Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages] (in Russian), volume 02, Moscow: Nauka, page 161
- Skok, Petar (1971) Etimologijski rječnik hrvatskoga ili srpskoga jezika (in Serbo-Croatian), volume I, Zagreb: JAZU, page 178ff
- Mallory, J. P.; Adams, D. Q., editors (1997) Encyclopedia of Indo-European culture, London, Chicago: Fitzroy Dearborn Publishers, page 161
- Beekes, Robert S. P. (2010) Etymological Dictionary of Greek (Leiden Indo-European Etymological Dictionary Series; 10), volume II, with the assistance of Lucien van Beek, Leiden, Boston: Brill, page 1543
- Rix, Helmut, editor (2001) Lexikon der indogermanischen Verben [Lexicon of Indo-European Verbs] (in German), 2nd edition, Wiesbaden: Dr. Ludwig Reichert Verlag, ISBN 3-89500-219-4, page 65
- Vasmer, Max (1964–1973), “бог”, in Etimologičeskij slovarʹ russkovo jazyka [Etymological Dictionary of the Russian Language] (in Russian), translated from German and supplemented by Trubačev O. N., Moscow: Progress
- Brückner, Aleksander (1927), “bóg”, in Słownik etymologiczny języka polskiego (in Polish)