@iapetoc:

Isn't it far more plausible that an Italic loan yielded Etruscan "Thewru", rather than Greek "Therion"?

I mean, cognates of this word are attested in many branches of Indo-European, all with the same meaning of "bull":

Latin "Taurus"
Oscan - "Taurom"
Greek "Tauros"
Gaulish "Tarvos"
Lithuanian "Tauras"
Lusitanian "Taurom"

I mean, I agree that the similarity with the aspiration in Greek definitely exists, but still. I don't quite see how "Therion" would yield "Thewru". That doesn't explain where the "W" comes from. It's more likely that a "U" would yield "W".

I mean, I agree that the base word probably wasn't Gaulish (or generally Celtic - since the Gauls arrived in Italy centuries after the Etruscans), since the -ur- to -ru- change is something found in all Celtic languages. But I think that an Italic or otherwise IE etymology (notice how the Lusitanian and Lithuanian words aren't all that different!) is viable, possibly via some intermediate stage of "Tavru-" or "Tawru-". Also, the Etruscans were known to aspirate other loanwords.