An Etymological Dictionary of the German Language/Annotated/Klapp

by Friedrich Kluge

Klapp, masculine, ‘clap, slap, blow,’ Modern High German only, adopted from Low German, like its cognates (Klappe, klappen, Klapps). Only klappern, verb, ‘to clatter,’ is current in Middle High German without any presumption of its being borrowed; perhaps it is onomatopoetic. Modern High German Klapp, ‘blow,’ is phonetically Middle High German klapf, klaf, masculine, ‘report, crack’; compare Klaff.