ביבער
־ס
דער
'beaver'

ETYMOLOGY

ON bjórr, OE beofor, English beaver, OS biƀar, biƀor, Dutch bever, OHG bibar, bibur, MHG biber, NHG Biber; from PGmc ✱bebura-; from PIE ✱bʰe-bʰr- < ✱bʰe-bʰr, gen. ✱bʰi-bʰr-ós 'beaver, the brown-colored one; cf. Lat. fiber, feber, Lithuanian bẽbras, bebrùs, Russian бобр, perhaps Sanskrit babhrú- 'red-brown'
{DW² 5: 179; Kluge/Seebold 2011: 119; Kroonen 2013: 56; Magnússon 60}
The comparison וויינען ווי אַ ביבער 'to cry like a beaver (i.e., like a baby)' appears to be a calque of Polish płakać jak bóbr (compare also Belarusian плакаць як бабёр).