An Etymological Dictionary of the German Language/plappern

by Friedrich Kluge

plappern, vb., ModHG. only, an onomatopoetic form of a lost stem, blab, which is also indicated by the equiv. MidHG. blępzen, OHG. blabbiȥôn, ‘to blab, babble’; allied to ModHG. (dial) and Du. blaffen, ‘to bark, yelp,’ Alem. plapen, E. to blab.