An Etymological Dictionary of the German Language/Krüppel
Krüppel, m., ‘cripple,’ from the equiv. MidHG. krüppel, krüpel, m.; it passed in the MidHG. period from LG. into HG.; Du. kreupel, E. cripple, MidE. and AS. cryppel, Scand. kryppell, kryplingr. The p of these forms is HG. pf (Alsat. Krüpfel), hence we must assume that HG. Krüppel was borrowed from LG. and MidG. Allied in the UpG. dials. to Swiss chrüft, chrüpfe, Suab. kropf, kruft, krüftle, Bav. krapf, kropf, ‘deformed person,’ and the cognate Bav. krüpfen, ‘to become crooked,’ akin to OIc. kroppr, kryppa, ‘hump,’ and the cognates discussed under Kropf. Besides Gr. γρυπός, ‘curved,’ we may also refer to OSlov. grŭbŭ, ‘back,’ ModSlov. grbanec, ‘wrinkle,’ Serv. grba, ‘hump’ (grbati se, ‘to stoop’).