​ dumpf, adjective, ‘damp, dull, heavy,’ Modern High German only; formed by the weakest stage of gradation from Middle High German dimpfen, strong verb, ‘to fume, smoke’; compare also Middle High German dumpfen, dümpfen, ‘to fume, damp.’ The original sense of the adjective is probably ‘smoky,’ i.e. ‘damp,’ or ‘dimming the sight and dulling the hearing’; dumpf appears in Dutch dompig, with the meaning ‘damp, gloomy.’ Perhaps the word is connected with dunkel; compare English dank.