The Collaborative International Dictionary of English v.0.48:

El Dorado \El` Do*ra"do\, pl. El Doradoes. [Sp., lit., the
   gilt (sc. land); el the + dorado gilt, p. p. of dorare to
   gild. Cf. Dorado.]
   1. A name given by the Spaniards in the 16th century to an
      imaginary country in the interior of South America,
      reputed to abound in gold and precious stones.
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   2. Any region of fabulous wealth; exceeding richness.
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            The whole comedy is a sort of El Dorado of wit. --T.
                                                  Moore.
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