An Etymological Dictionary of the German Language/Annotated/durch
durch, preposition, ‘through, owing to, by,’ from Middle High German durch. dur, ‘through,’ also ‘for the sake of,’ Old High German duruh, durh; compare Old Saxon thurh, Anglo-Saxon þurh, English through and thorough. Gothic þaírh, ‘through,’ with an abnormal vowel, is related to the Old High German dërh, ‘perforated,’ with which are connected Old High German durhil, durihil, Middle High German dürhel, dürkel, ‘pierced, porous,’ Anglo-Saxon þŷrel (for þyrhil), ‘hole’ (compare Nüster), as well as Gothic þaírkô, feminine, ‘hole’ (k, from kk, for kn?). The preposition might easily be a case of an older adjective, perhaps the accusative neuter. Besides the passive meaning of Old High German dërh, ‘pierced,’ an active sense, ‘piercing,’ may also be added. The base þerh would be best defined by ‘to pierce, penetrate,’ which recalls the High German dringen; the former is based upon a pre-Teutonic root terk, the latter upon a root trenk. The connection with Latin trans is exceedingly problematical.