Source : Webster's Revised Unabridged Dictionary (1913)

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.

            [Egypt] hath many shrewd havens, because of the
            great rocks that ben strong and dangerous to pass
            by.                                   --Sir J.
                                                  Mandeville.

            Every of this happy number That have endured shrewd
            days and nights with us.              --Shak.

   2. Artful; wily; cunning; arch.

            These women are shrewd tempters with their tongues.
                                                  --Shak.

   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.

            Professing to despise the ill opinion of mankind
            creates a shrewd suspicion that we have deserved it.
                                                  --Secker.

   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. -- {Shrewd"ly}, adv. --
          {Shrewd"ness}, n.

Source : WordNet®

shrewdly
     adv : in a shrewd manner; "he invested his fortune astutely" [syn:
            {astutely}, {sagaciously}, {sapiently}]