homonymy

from WordNet (r) 3.0 (2006)

homonymy
    n 1: the relation between two words that are spelled the same
         way but differ in meaning or the relation between two words
         that are pronounced the same way but differ in meaning

from The Collaborative International Dictionary of English v.0.48

Homonymy \Ho*mon"y*my\, n. [Gr. ?: cf. F. homonymie.]
   1. Sameness of name or designation; identity in relations.
      --Holland.
      [1913 Webster]

            Homonymy may be as well in place as in persons.
                                                  --Fuller.
      [1913 Webster]

   2. Sameness of name or designation of things or persons which
      are different; ambiguity.
      [1913 Webster]