An Etymological Dictionary of the German Language/Treber
Treber, plur., ‘husks, grains,’ from the equiv. MidHG. tręber, OHG. trębir, plur.; the corresponding sing. would be trab. Comp. Ic. draf, Du. draf, ‘sediment of a brewing’ (to which drabbe, ‘lees,’ is allied), AS. drœf, E. draff, ‘lees, refuse, dregs’ (late AS. drabbe, ‘lees, dregs, dirt,’ whence E. drab, applied to colour and a woman). If the medial ƀ of the Teut. base draboz, n., could have originated in a guttural, the word might be compared with OIc. dregg (equiv. to E. dregs), and hence be probably allied to Lat. frăces, ‘grounds, dregs of oil’; Aryan root dhraq?. It seems to be also connected more remotely with Trester, ‘husks, skins (of grapes).’