The Collaborative International Dictionary of English v.0.48:

Richness \Rich"ness\, n.
   The quality or state of being rich (in any sense of the
   adjective).
   [1913 Webster]

WordNet (r) 3.0 (2006):

richness
    n 1: the property of being extremely abundant; "the profusion of
         detail"; "the idiomatic richness of English" [syn:
         profusion, profuseness, richness, cornucopia]
    2: abundant wealth; "they studied forerunners of richness or
       poverty"; "the richness all around unsettled him for he had
       expected to find poverty" [syn: affluence, richness]
    3: the property of a sensation that is rich and pleasing; "the
       music had a fullness that echoed through the hall"; "the
       cheap wine had no body, no mellowness"; "he was well aware of
       the richness of his own appearance" [syn: fullness,
       mellowness, richness]
    4: the quality of having high intrinsic value; "the richness of
       the mines and pastureland"; "the cut of her clothes and the
       richness of the fabric were distinctive"
    5: the property of producing abundantly and sustaining vigorous
       and luxuriant growth; "he praised the richness of the soil";
       "weeds lovely in their rankness" [syn: richness,
       rankness, prolificacy, fertility]
    6: a strong deep vividness of hue; "the fire-light gave a
       richness of coloring to that side of the room"
    7: splendid or imposing in size or appearance; "the grandness of
       the architecture"; "impressed by the richness of the flora"
       [syn: impressiveness, grandness, magnificence,
       richness]