Source : Webster's Revised Unabridged Dictionary (1913)

Clairvoyance \Clair*voy"ance\, n. [F.]
   A power, attributed to some persons while in a mesmeric
   state, of discering objects not perceptible by the senses in
   their normal condition.

Source : WordNet®

clairvoyance
     n : apparent power to perceive things that are not present to
         the senses [syn: {second sight}, {extrasensory perception},
          {E.S.P.}, {ESP}]