[1] : The Collaborative International Dictionary of English v.0.48

shrewd \shrewd\, a. compar. shrewder; superl. shrewdest.
   originally the p. p. of shrew, v.t.
   1. inclining to shrew; disposing to curse or scold; hence,
      vicious; malicious; evil; wicked; mischievous; vexatious;
      rough; unfair; shrewish. obs. --chaucer.
      1913 webster

            egypt hath many shrewd havens, because of the
            great rocks that ben strong and dangerous to pass
            by.                                   --sir j.
                                                  mandeville.
      1913 webster

            every of this happy number
            that have endured shrewd days and nights with us.
                                                  --shak.
      1913 webster

   2. artful; wily; cunning; arch.
      1913 webster

            these women are shrewd tempters with their tongues.
                                                  --shak.
      1913 webster

   3. able or clever in practical affairs; sharp in business;
      astute; sharp-witted; sagacious; keen; as, a shrewd
      observer; a shrewd design; a shrewd reply.
      1913 webster

            professing to despise the ill opinion of mankind
            creates a shrewd suspicion that we have deserved it.
                                                  --secker.
      1913 webster

   syn: keen; critical; subtle; artful; astute; sagacious;
        discerning; acute; penetrating.

   usage: shrewd, sagacious. one who is shrewd is keen to
          detect errors, to penetrate disguises, to foresee and
          guard against the selfishness of others. shrewd is a
          word of less dignity than sagacious, which implies a
          comprehensive as well as penetrating mind, whereas
          shrewd does not.
          1913 webster -- shrewd"ly, adv. -- shrewd"ness,
          n.
          1913 webster
see also:
shrewder shrewdest shrewd sagacious shrewd"ly shrewd"ness 

[2] : WordNet (r) 2.0

shrewdness
     n : intelligence manifested by being astute as in business
         dealings syn: astuteness, perspicacity, perspicaciousness
see also:
astuteness perspicacity perspicaciousness 

[3] : Moby Thesaurus II by Grady Ward, 1.0

57 moby thesaurus words for "shrewdness":
   italian hand, acumen, acuteness, animal cunning, art, artfulness,
   artifice, astuteness, cageyness, callidity, canniness, cleverness,
   craft, craftiness, cunning, cunningness, deviousness, discernment,
   discrimination, fine italian hand, finesse, foxiness, gamesmanship,
   guile, guilefulness, ingeniousness, insidiousness, inventiveness,
   keenness, low cunning, one-upmanship, pawkiness, penetration,
   percipience, perspicacity, readiness, resourcefulness,
   satanic cunning, sharpness, shiftiness, slickness, slipperiness,
   slyness, sneakiness, sophistry, stealth, stealthiness, subtility,
   subtilty, subtleness, subtlety, suppleness, trickiness, wariness,
   wiles, wiliness, wit

Shrewdness >> S Words
Shrewdness, definition of term: Shrewdness
shrewdness_pag1.html