Source : Webster's Revised Unabridged Dictionary (1913)

Sagacious \Sa*ga"cious\, a. [L. sagax, sagacis, akin to sagire
   to perceive quickly or keenly, and probably to E. seek. See
   {Seek}, and cf. {Presage}.]
   1. Of quick sense perceptions; keen-scented; skilled in
      following a trail.

            Sagacious of his quarry from so far.  --Milton.

   2. Hence, of quick intellectual perceptions; of keen
      penetration and judgment; discerning and judicious;
      knowing; far-sighted; shrewd; sage; wise; as, a sagacious
      man; a sagacious remark.

            Instinct . . . makes them, many times, sagacious
            above our apprehension.               --Dr. H. More.

            Only sagacious heads light on these observations,
            and reduce them into general propositions. --Locke.

   Syn: See {Shrewd}. -- {Sa*ga"cious*ly}, adv. --
        {Sa*ga"cious*ness}, n.

Source : WordNet®

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