Celtic *dubro- 'water' is attested on Old Irish dobur and Middle Welsh dwfr, dwr, as well as in Gaulish anthroponymy and toponomy (Dubra, Uerno-dubrum)1. Incomprehensibly, the Celtic specialist Ranko Matasović conflates this word with an homonymous adjetive (Middle Irish dobur 'black, unclean') corresponding to *dubu- 'dark'. On the other hand, some Indo-Europeanists have suggested a link with the same IE root found in *dubno- 'deep', which referred to the Underworld in ancient mythology. However, none of these proposals looks convincing to me2.
Fortunately, Delamarre quotes the seemingly related Illyrian gloss dúbris 'sea'3. This makes me think it could be related to Hebrew ʕbr, Arabic ʕbr-[u]- 'to inundate, to invade', conflated by Militarev with the homonymous root *ʕVbur- found in Akkadian ebēru 'to cross (water); to extend beyond (something)'4 and which in turn would derive from Afrasian *ʕa-bir- 'to travel (along a road), to pass by, to cross (rivers)', cognate to IE *per- 'to ferry'.
IMHO this would be part of the Paleo-IE 'water' complex root studied by the Spanish Indo-Europeanist Francisco Villar5, which includes *ab- (Celtic *abon-, Latin amnis 'river'), *up- (Lithuanian ùpē, Letonian upe 'river'), *a(:)p- (Sanskrit ā́paḥ 'water', Tocharian āp 'water, river').
This etymology would point to a post glacial environment where rapid rising sea levels caused great extensions of land to be flooded, as in the Black Sea Flood, first proposed by William Ryan and Walter Pitman in 19976. According to these authors, the former Black Sea was a freshwater lake feeded with glacial meltwater and whose level was 90 m below the Mediterranean. Around 5,600 BC, the rising sea level caused the Bosporus to broke, forming a giant cascade. This event caused the exode of the people living in the flooded areas (more than 150,000 km2 of land), contributing to the spreading of a flood myth in several cultures.
IMHO this would be part of the Paleo-IE 'water' complex root studied by the Spanish Indo-Europeanist Francisco Villar5, which includes *ab- (Celtic *abon-, Latin amnis 'river'), *up- (Lithuanian ùpē, Letonian upe 'river'), *a(:)p- (Sanskrit ā́paḥ 'water', Tocharian āp 'water, river').
This etymology would point to a post glacial environment where rapid rising sea levels caused great extensions of land to be flooded, as in the Black Sea Flood, first proposed by William Ryan and Walter Pitman in 19976. According to these authors, the former Black Sea was a freshwater lake feeded with glacial meltwater and whose level was 90 m below the Mediterranean. Around 5,600 BC, the rising sea level caused the Bosporus to broke, forming a giant cascade. This event caused the exode of the people living in the flooded areas (more than 150,000 km2 of land), contributing to the spreading of a flood myth in several cultures.
___________________
1 R. Matasović (2009): Etymological Dictionary of Proto-Celtic, p. 107.
2 Although my colleague Ishinan suggested a link to Classical Arabic dibār/dabra-h 'water channel', IMHO this is related to the other 'channel' words mentioned here.
3 X. Delamarre (2008): Dictionnaire de la langue gauloise, p. 151-152.
4 Another homonymous Semitic root reconstructed by Militarev is *ʕa/ibr- 'river bank', which I relate to Germanic *ōfVr- 'bank, shore'.
5 F. Villar et al. (2011): Lenguas, genes y culturas en la prehistoria de Europa y Asia suroccidental.
6 W. Ryan & W. Pitman (1998): Noah's Flood.
2 Although my colleague Ishinan suggested a link to Classical Arabic dibār/dabra-h 'water channel', IMHO this is related to the other 'channel' words mentioned here.
3 X. Delamarre (2008): Dictionnaire de la langue gauloise, p. 151-152.
4 Another homonymous Semitic root reconstructed by Militarev is *ʕa/ibr- 'river bank', which I relate to Germanic *ōfVr- 'bank, shore'.
5 F. Villar et al. (2011): Lenguas, genes y culturas en la prehistoria de Europa y Asia suroccidental.
6 W. Ryan & W. Pitman (1998): Noah's Flood.