The Collaborative International Dictionary of English v.0.48:

Clairvoyance \Clair*voy"ance\, n. [F.]
   A power, attributed to some persons while in a mesmeric
   state, of discerning objects not perceptible by the senses in
   their normal condition.
   [1913 Webster]

WordNet (r) 3.0 (2006):

clairvoyance
    n 1: apparent power to perceive things that are not present to
         the senses [syn: clairvoyance, second sight,
         extrasensory perception, E.S.P., ESP]