Source : Webster's Revised Unabridged Dictionary (1913)

Pithiness \Pith"i*ness\, n.
   The quality or state of being pithy.

Source : WordNet®

pithiness
     n : terseness and economy in writing and speaking achieved by
         expressing a great deal in just a few words [syn: {conciseness},
          {concision}, {succinctness}]