An Etymological Dictionary of the German Language/Annotated/dunkel

by Friedrich Kluge

dunkel, adjective, ‘dark, gloomy, obscure,’ with Middle German initial d; from Middle High German tunkel, ‘dark, dull, damp,’ Old High German tunchal (with the parallel form tunchar, Middle Low German dunker). By another stage of gradation Old Icelandic døkkr, Old Frisian djunk are formed from the same root; they presuppose a Gothic *diggs (pre-Teutonic dhengwos). The primitively allied English dank points to a connection with dumpf (Teutonic root dinq, dump).