Source : Webster's Revised Unabridged Dictionary (1913)

Skeptic \Skep"tic\, n. [Gr. skeptiko`s thoughtful, reflective,
   fr. ske`ptesqai to look carefully or about, to view,
   consider: cf. L. scepticus, F. sceptique. See {Scope}.]
   [Written also {sceptic}.]
   1. One who is yet undecided as to what is true; one who is
      looking or inquiring for what is true; an inquirer after
      facts or reasons.

Skeptic \Skep"tic\, Skeptical \Skep"tic*al\, a. [Written also
   sceptic, sceptical.]
   1. Of or pertaining to a sceptic or skepticism; characterized
      by skepticism; hesitating to admit the certainly of
      doctrines or principles; doubting of everything.

   2. (Theol.) Doubting or denying the truth of revelation, or
      the sacred Scriptures.

            The skeptical system subverts the whole foundation
            of morals.                            --R. Hall.
      -- {Skep"tac*al*ly}, adv. -- {Skep"tic*al*ness}, n.

Source : WordNet®

skeptic
     n : someone who habitually doubts accepted beliefs [syn: {sceptic},
          {doubter}]