Source : Webster's Revised Unabridged Dictionary (1913)

Tasteless \Taste"less\, a.
   1. Having no taste; insipid; flat; as, tasteless fruit.

   2. Destitute of the sense of taste; or of good taste; as, a
      tasteless age. --Orrery.

   3. Not in accordance with good taste; as, a tasteless
      arrangement of drapery. -- {Taste"less*ly}, adv. --
      {Taste"less*ness}, n.

Source : WordNet®

tastelessness
     n 1: the property of having no flavor [syn: {flavorlessness}, {flavourlessness},
           {savorlessness}, {savourlessness}]
     2: inelegance indicated by a lack of good taste [ant: {tastefulness}]