Source : Webster's Revised Unabridged Dictionary (1913)

Acatalepsy \A*cat"a*lep`sy\, n. [Gr. ?; 'a priv. + ? to seize,
   comprehend.]
   Incomprehensibility of things; the doctrine held by the
   ancient Skeptic philosophers, that human knowledge never
   amounts to certainty, but only to probability.