Source : Webster's Revised Unabridged Dictionary (1913)

Sagacity \Sa*gac"i*ty\, n. [L. sagacitas. See {Sagacious}.]
   The quality of being sagacious; quickness or acuteness of
   sense perceptions; keenness of discernment or penetration
   with soundness of judgment; shrewdness.

         Some [brutes] show that nice sagacity of smell.
                                                  --Cowper.

         Natural sagacity improved by generous education. --V.
                                                  Knox.

   Syn: Penetration; shrewdness; judiciousness.

   Usage: {Sagacity}, {Penetration}. Penetration enables us to
          enter into the depths of an abstruse subject, to
          detect motives, plans, etc. Sagacity adds to
          penetration a keen, practical judgment, which enables
          one to guard against the designs of others, and to
          turn everything to the best possible advantage.

Source : WordNet®

sagacity
     n 1: ability to make good judgments [syn: {sagaciousness}, {judgment},
           {judgement}, {discernment}]
     2: the trait of forming opinions by distinguishing and
        evaluating [syn: {judiciousness}, {sagaciousness}]