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]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "clairvoyance":
   ESP, a priori knowledge, anticipation, apprehension, astrology,
   augury, buddhi, clairsentience, command, comprehension, conception,
   conceptualization, crystal ball, crystal gazing,
   direct apprehension, divination, divining, extrasensory perception,
   foreboding, foreknowing, foreknowledge, foreseeability, foresight,
   forewisdom, fortunetelling, grasp, grip, haruspication, haruspicy,
   horoscopy, ideation, immediate cognition, insight, inspiration,
   intellection, intelligence, intuition, intuitionism,
   intuitive reason, intuitiveness, intuitivism,
   knowledge without thought, lucidity, mantic, mantology, mastery,
   mental grasp, palm-reading, palmistry, precognition, prehension,
   premonition, presage, prescience, presentiment, psychometry,
   pythonism, satori, savvy, second sight, second-sightedness,
   sixth sense, sorcery, subconscious knowledge,
   subconscious perception, understanding, unmediated perception,
   wisdom