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1. Having the capacity for thought and reason especially to a high degree
   "is there intelligent life in the universe?"
    
2. Possessing sound knowledge
   "intelligent readers";
   - well-informed, clued-up [Brit, informal], savvy [informal]
    
3. Exercising or showing good judgment
   "an intelligent solution";
   - healthy, levelheaded, level-headed, sound
    
4. Endowed with the capacity to reason
   - reasoning, thinking

See also: agile, apt, born, brainy [informal], bright, brilliant, clever, coruscating, innate, intelligence, natural, nimble, precocious, prehensile, quick, rational, ready, reasonable, scintillating, searching, sensible, smart, smart as a whip [informal], sophisticated, sparkling, trenchant

Antonym: stupid

Encyclopedia: Intelligent