From earlier rōbus (with change of nominative after the pattern of iecur), from Proto-Italic *rouβos ~ *rouβoses, from Proto-Indo-European *h₁rewdʰ- (“red”), named for its reddish hardwood and thus cognate to ruber.
Ćwicz mówienie i zapamiętywanie " robur " i wielu innych słów i zdań z łaciński .