An Etymological Dictionary of the German Language/Schlappe

by Friedrich Kluge

Schlappe (1.), f., ‘slipper,’ ModHG. only, from LG. slappe, winch is derived from LG. slapp, ‘loose.’

Schlappe (2.), f., ‘slap; discomfiture, defeat,’ ModHG. only, from LG. slappe; comp. MidE. slappe, E. slap; hence also in earlier ModHG. ‘slap in the face.’ From a HG. *slapfe is derived Ital. schiaffo, ‘slap in the face.’