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]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "sapient":
   authority, broad-minded, deep, discriminating, doctor, elder,
   elder statesman, erudite, great soul, guru, illuminate, intellect,
   intellectual, judicious, knowing, learned, lover of wisdom,
   mahatma, man of intellect, man of wisdom, mandarin, master,
   mastermind, mentor, oracle, philosopher, profound, prudent, rabbi,
   rishi, sage, sane, savant, scholar, scholarly, seer, sensible,
   starets, thinker, thinking, wise, wise as Solomon, wise man,
   wise old man