An Etymological Dictionary of the German Language/Annotated/mucken
mucken, verb, ‘to grumble,’ first occurs in early Modern High German, probably akin to late Middle High German mûgen, ‘to roar,’ which may be allied to μυκάομαι, ‘to roar’ (see Mücke). Perhaps it is also connected with Muckser; it is based on Middle High German muckzen, muchzen, Old High German muccazzen, ‘to whisper, grumble’; apparently, however, it is better connected with the Teutonic root mū̆k, ‘to pretend to know secrets,’ discussed under meuchel-. To this also belongs the simply Modern High German Mucker, ‘sulky person, grumbler,’ properly ‘religions hypocrite,’ in which sense the word first appeared in Jena in the early part of the 18th century to denote the adherents of the pietist theologian Buddeus.