Etymology
From Middle English quaken, from Old English cwacian (“to quake, tremble, chatter”), from Proto-Germanic *kwakōną (“to shake, quiver, tremble”), itself likely of imitative origin. Related to Old English cweċċan (“to shake, swing, move, vibrate, shake off, give up”) (see quitch), Dutch kwakkelen (“to ail, be ailing”), German Quackelei (“chattering”), Danish kvakle (“to bungle”), Latin vexō (“toss, shake violently, jostle, vex”), Irish bogadh (“a move, movement, shift, change”).