ESSJa treats it as as a single headword, Derksen as two (separating meanings "harrow" and "guarded entrance, barrier"), and Sławski as three ("harrow", "defended/defending object" and "membrane").
The meaning "harrow" is from Proto-Indo-European *bʰorh₃neh₂, o-grade derivation from *bʰerh₃- (“to hit with a sharp instrument”). Cognates include Latin forō (“to bore, pierce”), Old Norse bora (“to bore, drill”) and Ancient Greek φάρω (phárō), φάρος (pháros). From the same root also Common Slavic *bьrdo (“weaving comb, reed”), *boriti sę (“to fight”), and *borzda (“furrow”).
Sławski derives the set of meanings "protection, guard, defense; object of protecting, defending, gate, dam, barrier, fortification" as an action noun of the verb *borniti (“to guard, protect, defend”). Derksen legitimizes separate treatment due to the semantic difficulties of connecting Common Slavic *borti (“to fight, conquer”) as well as other Indo-European cognates (Latin feriō (“to hit, strike”), Old Norse berja (“to beat, hit”)) with the root *bʰerh₃- (“to hit with a sharp instrument”).
The third separate meaning "membrane" (on the basis of Czech bránice (“membrane, diaphragm”), Slovak branica (“membrane”) and Slovene brána, bránica (“membrane”) is with uncertainty reconstructed by Sławski, with various explanations of origin.
- guarded entrance, protection, barrier, defense
- (by extension) the object being defended/restrained or defending/restraining, especially fortified gate, dam, dike etc.
- East Slavic:
- South Slavic:
- West Slavic:
- Hungarian: borona
- “борона” in Max Vasmer (1986), Etimologičeskij slovarʹ russkogo jazyka [Etymological Dictionary of the Russian Language], in 4 vols (second edition), Moscow: Progress — Translated from German and supplemented by O. N. Trubačóv
- Rick Derksen (2008), Etymological Dictionary of the Slavic Inherited Lexicon, Brill: Leiden-Boston, page 56f
- “*borna” in Oleg Trubačóv (ed.) (1974–), Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages], Moscow: Nauka, volume 02, page 204ff
- Franciszek Sławski (ed.). (1974–2001), Słownik prasłowiański, Wrocław: Polskiej Akademii Nauk, volume I, page 324f