The Collaborative International Dictionary of English v.0.48:

Sapient \Sa"pi*ent\, a. [L. sapiens, -entis, p. pr. of sapere to
   taste, to have sense, to know. See Sage, a.]
   Wise; sage; discerning; -- often in irony or contempt.
   [1913 Webster]

         Where the sapient king
         Held dalliance with his fair Egyptian spouse. --Milton.
   [1913 Webster]

   Syn: Sage; sagacious; knowing; wise; discerning.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sapient
    adj 1: acutely insightful and wise; "much too perspicacious to
           be taken in by such a spurious argument"; "observant and
           thoughtful, he was given to asking sagacious questions";
           "a source of valuable insights and sapient advice to
           educators" [syn: perspicacious, sagacious, sapient]