Source : Webster's Revised Unabridged Dictionary (1913)

Vapid \Vap"id\, a. [L. vapidus having lost its lire and spirit,
   vapid; akin to vappa vapid wine, vapor vapor. See {Vapor}.]
   Having lost its life and spirit; dead; spiritless; insipid;
   flat; dull; unanimated; as, vapid beer; a vapid speech; a
   vapid state of the blood.

         A cheap, bloodless reformation, a guiltless liberty,
         appear flat and vapid to their taste.    --Burke.
   -- {Vap"id*ly}, adv. -- {Vap"id*ness}, n.

Source : WordNet®

vapidness
     n : the quality of being vapid and unsophisticated [syn: {jejunity},
          {jejuneness}, {tameness}, {vapidity}]