On the Etymology of the River-name Ruhr and Some of its Central-European Cognates: Celtic or not Celtic – That is the Question

Traditionally, the river-nameRuhr and its siblings are said to be derived from the root PIE *reuH - 'tear up, dig up' (outdated form of reconstruction: *reu-, *reu-, *ru - [IEW 868]) and they are regarded as part of the so-called 'Old European hydronymy'. Reviewing the literature on the river-namesRuhr, Rur, Rulles, and the place-name Ruhla, we find that two different pre-forms tend to be reconstructed, *rūr° and * rur°. It can be shown that by applying a sound-law generally accepted in Indo-European linguistics (Dybo's Law), the pre-form must be reconstructed as * rur°, even if we start from the root mentioned above (PIE *ruH-ró- > Late (Western-)PIE * ruró-). But as the semantics of that root appears to be not very satisfactory, further roots are tried as starting-points for etymologizing the names in question. The following roots are possible from a structural/phonological point of view: a) PIE *h3reuH- 'shout, roar': PIE *h3ruH-ró- > late PIE *(h3)ruró -; b) PIE *h2 reu - 'shine, sparkle (reddishly)': PIE * h2 ru- ró- > late PIE *( h2 )ruró -; c) PIE *h3 reu - 'move quickly, dash forward': PIE * h3 ru- ró- > late PIE *(h3)ruró -. Two language groups are attested in the areas, where the rivers are situated: Germanic and Celtic. But out of the three roots just mentioned none is continued in Germanic and only PIE *h2 reu- 'shine, sparkle (reddishly)' and PIE *h3 reu- 'move quickly, dash forward' are continued in Celtic. A formation from another root, PIE * preu- 'jump' (* pru-ró- > PCelt. * []ruró-) would give the correct result in Celtic, but the root does not have descendants in any Celtic language. Thus we arrive at the result that the river names, which are all on potentially Celtic territory, are most probably Celtic. The names meant either 'the quick(ly flowing) one' or 'the gleaming one' – both solutions are semantically typical for the oldest layers of hydronyms. No decision between these two results is possible. But as we can offer an etymology now anchored in a single Indo-European language (group), there is no reason anymore to regard these names as 'voreinzelsprachlich' and thus part of the 'Old European hydronymy'. It remains to be researched, whether all the hydronyms traditionally derived from the root PIE *reuH - 'tear up, dig up' (outdated form of reconstruction: *reu-, *reu-, *ru-) are really necessarily to be connected with this root, now that three other roots (PIE *h3reuH- 'shout, roar', PIE * h2reu- 'shine, sparkle (reddishly)', PIE *h3 reu - 'move quickly, dash forward') offer phonologically and semantically possible starting-points for etymologies.