An Etymological Dictionary of the German Language/Annotated/dämmern
dämmern, verb, ‘to grow dusk, dawn,’ from Middle High German dëmere, feminine (also even Middle High German dëmerunge, feminine), Old High German dëmar, neuter, ‘crepusculum,’ a derivative of a Teutonic root þem, Aryan tem, ‘to be dusk’ (see also dämisch). Old Saxon preserves in the Heliand the cognate adjective thimm, ‘gloomy’; allied to Middle Dutch and Middle Low German deemster, ‘dark.’ A part from Teutonic the assumed root tem, meaning ‘to grow dusk,’ is widely diffused; Sanscrit tamas, ‘darkness’ (exactly corresponding to Old High German dëmar), tamrá-s, ‘obscuring, stifling’; támisrâ, feminine, ‘dark night’; Irish temel, ‘darkness,’ temen, ‘dark grey.’ With the latter words Latin tenebrœ, ‘darkness,’ is connected (br in Latin from sr; n for m on account of the following labial, a process of differentiation); Old Slovenian tĭma, ‘darkness,’ Lithuanian tamsùs, ‘dark,’ tamsà, feminine, ‘dusk,’ témti, ‘to grow dusk.’ In the earlier German periods we have further Middle High German dinster, Old High German dinstar, which are so related to Sanscrit támisrâ, ‘night,’ and Latin tenebrœ, as to imply a Gothic þinstra- as an adjective stem; in that case t has intruded between s and r, as in Schwester. With regard to Middle High German dinster compare also Modern High German düster and finster.