The semantic connection between "white" and "swamp, mud" is not obvious, but has been attested in many languages. Beside the mentioned Lithuanian, also in e.g., Old Polish biel (“mud, swamp”) (< *bělь, from *bělъ (“white”)). This is probably due to the widespread presence of the marsh grass called cottongrass (genus Eriophorum), whose the white fluffy seed heads are white, or the color of the dried clay taking light hue, depending on soil.
Though formally and semantically derivable from Proto-Indo-European *bʰelH- (“white”), with cognates such as Albanian baltë (“mud”), Romanian baltă (“mud, swamp”) and Greek βάλτος (váltos, “swamp”), it is often considered an Illyrian substratum word due to the fact that most of the cognates are restricted to the Balkan peninsula, or its surroundings. However, these can also be borrowings from early Slavic; indirect evidence shows that the Slavic liquid metathesis and pleophony happened well after the spread of Slavic to the Balkans and the word must have been pronounced as *balta or *bolto as recently as the late 8th century.
- East Slavic:
- South Slavic:
- Non-Slavic languages:
- → Yiddish: בלאָטע (blote)
- Vasmer (Fasmer), Max (Maks) (1964–1973), “болото”, in Etimologičeskij slovarʹ russkovo jazyka [Etymological Dictionary of the Russian Language] (in Russian), translated from German and supplemented by Trubačóv Oleg, Moscow: Progress
- Černyx, P. Ja. (1999), “болото”, in Istoriko-etimologičeskij slovarʹ russkovo jazyka [Historical-Etymological Dictionary of the Russian Language] (in Russian), volume 1, 3rd reprint edition, Moscow: Russkij jazyk, page 101
- Sławski, Franciszek, editor (1974) Słownik prasłowiański (in Polish), volume I, Wrocław: Polska Akademia Nauk, page 311f
- Trubačóv, Oleg, editor (1975), “*bolto”, in Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages] (in Russian), volume 02, Moscow: Nauka, page 179
- ^ Derksen, Rick (2008), “*bòlto”, in Etymological Dictionary of the Slavic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 4), Leiden, Boston: Brill, →ISBN, page 53
- ^ Kapović, Mate (2007), “The Development of Proto-Slavic Quantity”, in Wiener Slavistisches Jahrbuch, University of Vienna, page 5: “*bőlto”
- ^ Olander, Thomas (2001), “bolto”, in Common Slavic accentological word list, Copenhagen: Editiones Olander: “a (SA 151; PR 132)”