An Etymological Dictionary of the German Language/Annotated/tapfer
tapfer, adjective, ‘brave, variant, bold,’ from Middle High German tapfer (dapfer, tapfel), ‘firm, pressed, full, weighty, important’ (only in late Middle High German brave), Old High German tapfar, ‘heavy, weighty, important’; compare Dutch dapper, ‘brave, much,’ English dapper. The connection in meaning with Old Slovenian doblĭ, ‘strong, able,’ debelŭ, ‘stout,’ and dobrŭ, ‘beautiful, good,’ is quite clear, but it is difficult to show how it is related to the corresponding Old Icelandic dapr, ‘sad’; note, however, Modern High German dreist, ‘bold, audacious,’ Old High German drîsti, Old Low German thrîsti, compared with Latin trîstis.