An Etymological Dictionary of the German Language/Biber
Biber, m., ‘beaver,’ from the equiv. MidHG. biber, OHG. bibar, m.; it corresponds to AS. beofor, E. beaver, Du. bever, OIc. bjórr, Goth. *bibrus, A term common to the Aryan family, originally eignilying a ‘brown’ aquatic animal; Lat. fiber (OGall. Bibracte), OSlov. bebrŭ, Lith. běbrus (most frequently dábras), ‘beaver.’ OInd. babhrús as an adj. means ‘brown,’ as a subst. masc. ‘great ichneumon’; bhe-bhrú-s is a reduplicated form of the root bher in Bär and braun. The primitive tribe from which the Indo-Teutons are descended had ere its dispersion several fully developed names of animals; comp. Hund, Kuh, Maus, Wolf, &c. The Teut. word had at an early period supplanted the Lat. fiber in Rom., Late Lat. biber, Ital. bevero, Span. bibaro, Fr. bièvre, from Teut. bebru-, bibru-.