An Etymological Dictionary of the German Language/Annotated/tief
tief, adjective, ‘deep, profound, low,’ from the equivalent Middle High German tief, Old High German tiof; corresponding to Old Saxon diop, Dutch diep, Anglo-Saxon deóp, English deep (depth and to dip), Old Icelandic djópr, and Gothic diups, ‘deep.’ The common Teutonic adjective diupa-, of which Modern High German taufen is a factitive, belongs to a Teutonic root dū̆p, the variant of which, dū̆b, appears in Anglo-Saxon dŷfan, English to dive (see Taube), as well as in English dub. Compare Welsh dwfn, Old Irish fudomain, Lithuanian dubùs, ‘deep, hollow,’ Old Slovenian duplĭ, ‘hollow’ (see Tobel), from an Aryan root dhub, dhup. For a nasalised Teutonic root dump, see Tümpel.