The Collaborative International Dictionary of English v.0.48:

Amphibology \Am`phi*bol"o*gy\ ([a^]m`f[i^]*b[-o]l"[-o]*j[y^]),
   n.; pl. Amphibologies (-j[i^]z). [L. amphibologia, for
   amphibolia, fr. Gr. 'amfiboli`a, with the ending -logia as if
   fr. Gr. 'amfi`bolos ambiguous + lo`gos speech: cf. F.
   amphibologie. See Amphiboly.]
   A phrase, discourse, or proposition, susceptible of two
   interpretations; and hence, of uncertain meaning. It differs
   from equivocation, which arises from the twofold sense of a
   single term.
   [1913 Webster]

WordNet (r) 3.0 (2006):

amphibology
    n 1: an ambiguous grammatical construction; e.g., `they are
         flying planes' can mean either that someone is flying
         planes or that something is flying planes [syn:
         amphibology, amphiboly]