An Etymological Dictionary of the German Language/deftig

by Friedrich Kluge

deftig, adj., ModHG. only, from LG. destig; the latter, with E. daft, AS. gedœft, ‘mild, meek, gentle’ (Goth. gadaban, ‘to be fitting’), and perhaps with HG. tapfer, is derived from a Teut. root dab, dap. See tapfer.