The Collaborative International Dictionary of English v.0.48:

Marvelous \Mar"vel*ous\, a. [OE. merveillous, OF. merveillos, F.
   Merveilleux. See Marvel, n.] [Written also marvellous.]
   1. Exciting wonder or surprise; astonishing; wonderful.
      [1913 Webster]

            This is the Lord's doing; it is marvelous in our
            eyes.                                 --Ps. cxiii.
                                                  23.
      [1913 Webster]

   2. Partaking of the character of miracle, or supernatural
      power; incredible; so improbable as to defy belief.
      [1913 Webster +PJC]

            The marvelous fable includes whatever is
            supernatural, and especially the machines of the
            gods.                                 --Pope.
      [1913 Webster]

   The marvelous, that which exceeds natural power, or is
      preternatural; that which is wonderful; -- opposed to the
      probable.
      [1913 Webster]

   Syn: Wonderful; astonishing; surprising; strange; improbable;
        incredible.

   Usage: Marvelous, Wonderful. We speak of a thing as
          wonderful when it awakens our surprise and admiration;
          as marvelous when it is so much out of the ordinary
          course of things as to seem nearly or quite
          incredible.
          [1913 Webster]