The Collaborative International Dictionary of English v.0.48:

Cornucopia \Cor`nu*co"pi*a\ (k[^o]r`n[-u]*k[=o]"p[i^]*[.a]), n.;
   pl. Cornucopias (-[.a]z). [L. cornu copiae horn of plenty.
   See Horn, and Copious.]
   1. The horn of plenty, from which fruits and flowers are
      represented as issuing. It is an emblem of abundance.
      [1913 Webster]

   2. pl. (Bot.) A genus of grasses bearing spikes of flowers
      resembling the cornucopia in form.
      [1913 Webster]

   Note: Some writers maintain that this word should be written,
         in the singular, cornu copi[ae], and in the plural,
         cornua copi[ae].
         [1913 Webster] Cornute

WordNet (r) 3.0 (2006):

cornucopia
    n 1: a goat's horn filled with grain and flowers and fruit
         symbolizing prosperity [syn: horn of plenty,
         cornucopia]
    2: the property of being extremely abundant; "the profusion of
       detail"; "the idiomatic richness of English" [syn:
       profusion, profuseness, richness, cornucopia]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "cornucopia":
   abundance, accumulation, amassment, backlog, bonanza, budget,
   collection, commissariat, commissary, cumulation, dump,
   endless supply, font, fount, fountain, gold mine, heap, hoard,
   horn of Amalthea, horn of plenty, inventory, larder, lode, mass,
   material, materials, materiel, mine, munitions, pile, plenitude,
   plenty, provisionment, provisions, quarry, rations, repertoire,
   repertory, resource, rick, source, source of supply, spring, stack,
   staple, stock, stock-in-trade, stockpile, store, stores, supplies,
   supply on hand, treasure, treasury, vein, well, wellspring