[syn: intelligent, reasoning(a), thinking(a)]
The Collaborative International Dictionary of English v.0.48:
Intelligent \In*tel"li*gent\, a. [L. intelligens, intellegens,
   -entis, p. pr. of intelligere, intellegere, to perceive;
   inter between + legere to gather, collect, choose: cf. F.
   intelligent. See Legend.]
   [1913 Webster]
   1. Endowed with the faculty of understanding or reason; as,
      man is an intelligent being.
      [1913 Webster]
   2. Possessed of a high level of intelligence, education, or
      judgment; knowing; sensible; skilled; exhibiting high
      intelligence; as, an intelligent young man; an intelligent
      architect; an intelligent answer.
      [1913 Webster]
   3. Cognizant; aware; communicative. [Obs.]
      [1913 Webster]
            Intelligent of seasons.               --Milton.
      [1913 Webster]
            Which are to France the spies and speculations
            Intelligent of our state.             --Shak.
   Syn: Sensible; understanding. See Sensible.
        [1913 Webster]
WordNet (r) 3.0 (2006):
intelligent
    adj 1: having the capacity for thought and reason especially to
           a high degree; "is there intelligent life in the
           universe?"; "an intelligent question" [ant: stupid,
           unintelligent]
    2: possessing sound knowledge; "well-informed readers" [syn:
       intelligent, well-informed]
    3: exercising or showing good judgment; "healthy scepticism"; "a
       healthy fear of rattlesnakes"; "the healthy attitude of
       French laws"; "healthy relations between labor and
       management"; "an intelligent solution"; "a sound approach to
       the problem"; "sound advice"; "no sound explanation for his
       decision" [syn: healthy, intelligent, levelheaded,
       level-headed, sound]
    4: endowed with the capacity to reason [syn: intelligent,
       reasoning(a), thinking(a)]
Moby Thesaurus II by Grady Ward, 1.0:
94 Moby Thesaurus words for "intelligent":
   acute, adroit, alert, all-knowing, apperceptive, appercipient,
   apprehending, apprehensive, apt, astute, au fait, aware, brainy,
   bright, brilliant, canny, cerebral, clever, cognizant,
   comprehending, conceptive, conceptual, conscious, consequent,
   cunning, discerning, discursive, docile, educable, endopsychic,
   enlightened, erudite, facile, formable, gifted, ideational,
   impressionable, ingenious, insightful, instructable, intellectual,
   internal, keen, knowing, knowledgeable, logical, malleable, mental,
   mindful, moldable, motivated, noetic, noological, not so dumb,
   omniscient, perceptive, percipient, perspicacious, phrenic,
   plastic, pliable, prehensile, psychic, psychologic, quick,
   quick-witted, rational, ready, reasonable, reasoning, receptive,
   ripe for instruction, sagacious, sage, sane, savvy, schoolable,
   sensible, sharp, shrewd, smart, sophic, sound, spiritual,
   strong-minded, subjective, susceptible, teachable, thinking,
   thirsty for knowledge, trainable, understanding, willing, wise