An Etymological Dictionary of the German Language/Annotated/Flaum
Flaum, masculine (Up.German Pflaum also), ‘down,’ from Middle High German phlûme, feminine, Old High German pflûma, ‘down,’ from Latin plûma, whence also Anglo-Saxon plûmfëþere. As the shifting of the initial sound proves, however, the word must have been borrowed in the earlier Old High German period; compare the Old Irish word (also derived from the Latin) clúm, ‘feather’ (Old Welsh plumauc, ‘pillow’). Scandinavian and English have for Flaum an apparently genuine Teutonic word (see Daune. It is certainly recorded by Pliny that Teutonic tribes in the olden time sent flocks of geese to Rome; but perhaps it was only ‘down’ (see also Flocke), which was valuable to the Southerners, and so the Latin pluma may hare been introduced into Teutonic at an early period. The initial f of the Modern High German form for pf may be due to the connection with Feder.