An Etymological Dictionary of the German Language/Annotated/flennen

by Friedrich Kluge

flennen, verb, ‘to weep ruefully, grin,’ from Middle High German *vlennen; akin to Old High German flannên, ‘to make a wry face,’ from pre-Teutonic *flaznan?. Root flas, from pre-Teutonic plos, in Latin plôrare, ‘to weep’?.