Source : Webster's Revised Unabridged Dictionary (1913)

Acuteness \A*cute"ness\, n.
   1. The quality of being acute or pointed; sharpness; as, the
      acuteness of an angle.

   2. The faculty of nice discernment or perception; acumen;
      keenness; sharpness; sensitiveness; -- applied to the
      senses, or the understanding. By acuteness of feeling, we
      perceive small objects or slight impressions: by acuteness
      of intellect, we discern nice distinctions.

            Perhaps, also, he felt his professional acuteness
            interested in bringing it to a successful close.
                                                  --Sir W.
                                                  Scott.

   3. Shrillness; high pitch; -- said of sounds.

   4. (Med.) Violence of a disease, which brings it speedily to
      a crisis.

   Syn: Penetration; sagacity; keenness; ingenuity; shrewdness;
        subtlety; sharp-wittedness.

Source : WordNet®

acuteness
     n 1: a quick and penetrating intelligence; "he argued with great
          acuteness"; "I admired the keenness of his mind" [syn: {acuity},
           {sharpness}, {keenness}]
     2: the quality of having a sharp edge or point [ant: {obtuseness}]