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]