The Collaborative International Dictionary of English v.0.48:

Riches \Rich"es\, n. pl. [OE. richesse, F. richesse, from riche
   rich, of German origin. See Rich,a.]
   1. That which makes one rich; an abundance of land, goods,
      money, or other property; wealth; opulence; affluence.
      [1913 Webster]

            Riches do not consist in having more gold and
            silver, but in having more in proportion, than our
            neighbors.                            --Locke.
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   2. That which appears rich, sumptuous, precious, or the like.
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            The riche of heaven's pavement, trodden gold.
                                                  --Milton.
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   Note: Richesse, the older form of this word, was in the
         singular number. The form riches, however, is plural in
         appearance, and has now come to be used as a plural.
         [1913 Webster]

               Against the richesses of this world shall they
               have misease of poverty.           --Chaucer.
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               In one hour so great riches is come to nought.
                                                  --Rev. xviii.
                                                  17.
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               And for that riches where is my deserving?
                                                  --Shak.
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   Syn: Wealth; opulence; affluence; wealthiness; richness;
        plenty; abundance.
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WordNet (r) 3.0 (2006):

riches
    n 1: an abundance of material possessions and resources [syn:
         wealth, riches]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "riches":
   abundance, affluence, assets, bottomless purse, bulging purse,
   easy circumstances, embarras de richesses, fortune, gold,
   handsome fortune, high income, high tax bracket, independence,
   lucre, luxuriousness, mammon, material wealth, means, money,
   money to burn, moneybags, opulence, opulency, pelf, plenty,
   possessions, property, prosperity, prosperousness, resources,
   richness, six-figure income, substance, treasure, upper bracket,
   wealth, wealthiness, worth



The Devil's Dictionary (1881-1906):

RICHES, n.

        A gift from Heaven signifying, "This is my beloved son, in
    whom I am well pleased."
                                                   John D. Rockefeller

        The reward of toil and virtue.
                                                           J.P. Morgan

        The sayings of many in the hands of one.
                                                           Eugene Debs

    To these excellent definitions the inspired lexicographer feels
that he can add nothing of value.