An Etymological Dictionary of the German Language/Annotated/Blatt
Blatt, neuter, ‘leaf, blade, newspaper,’ from the equivalent Middle High German and Old High German blat neuter’; compare the corresponding Dutch blad, Anglo-Saxon blœd, ‘leaf,’ English blade; Gothic *blaþ. The dental of these cognates seems to be a suffix; bla- from pre-Teutonic bhlo-, as well as Latin fol-ium, Greek, φύλλον, ‘leaf,’ may have been formed from a root bhol, bhlô. It is uncertain whether Gothic *blada- is really a participle with an Ayran suffix tó-, with the meaning ‘having ceased to bloom’ or ‘fully grown.’ See blühen.