An Etymological Dictionary of the German Language/Krampf
Krampf, m., ‘cramp, spasm, convulsion,’ from the equiv. MidHG. and OHG. krampf (OHG. also chrampfo); comp. OSax. cramp, Du. kramp, f., E. cramp; the common West Teut. term for ‘cramp’; orig. an adjectival subst. from OHG. chrampf, ‘curved,’ OIc. krappr (normal for *krampr), ‘narrow, pressed close.’ The Teut. stem krampa- has numerous cognates in G.; besides the LG. loan-words krampe, krämpe, krämpel, we may mention OHG. chrampf, ‘hook, border,’ chrimpfan, MidHG. krimpfen, ‘to contract in a crooked or spasmodic fashion,’ MidHG. krimpf, adj., ‘crooked’ masc. subst. ‘cramp’; ModHG. krumm is also allied, as is indicated by its OHG. and MidHG. variant krumpf, ‘bent, twisted.’ Comp. krumm, and OHG. chrimpfan, MidHG. krimpfen, ‘to be convulsed,’ ModDu. krimpen, ‘to draw in, shrivel,’ MidE. crimpil, ‘wrinkle,’ crumbe, ‘hook,’ crumpe, ‘crump,’ E. to crimple, ‘to contract,’ &c.; OIc. krappr, ‘narrow,’ and its nominal vb. kreppa, ‘to compress.’ Comp. Krüppel and Krapfen.