An Etymological Dictionary of the German Language/Annotated/flach

by Friedrich Kluge

flach, adjective, ‘flat, shallow, superficial,’ from Middle High German vlach, Old High German flah(hh), adjective, ‘flat, smooth’; compare Dutch vlak, ‘even.’ Akin to the graded forms Anglo-Saxon flôc, English flook, fluke (‘flounder’), North English flook-footed, ‘flat-footed.’ This suggests Latin plaga, ‘district,’ or more probably, on account of its meaning, Old Slovenian plosku, ‘flat’; Latin plânus scarcely represents *plagnus (see Flur); related to Greek πλάξ (stem πλακ), ‘surface,’ Greek πλακοῦς, Latin placenta, ‘cake.’ But English flat, Old Icelandic flatr, Old High German flaȥ, ‘flat, level,’ have nothing to do with flach. A Middle German and Low German parallel form of flach is mentioned under Blachfeld.