An Etymological Dictionary of the German Language/gackern

by Friedrich Kluge

gackern, gacksen, vb., ‘to cackle, chatter,’ simply ModHG.; imitative forms like MidHG. gâgen, ‘to cackle like a goose.’ akin to Du. gagelen, ‘to gabble,’ and even in OHG. gackizôn, ‘to mutter,’ gagizôn, gackazzen, ‘to bawl,’ MidHG. gagzen, ‘to cluck like a hen laying.’ Comp. Scand. gagga, ‘to howl like a fox,’ gagl, ‘wild goose,’ E. to gaggle.