The Collaborative International Dictionary of English v.0.48:

Ambiguity \Am`bi*gu"i*ty\, n.; pl. Ambiguities. [L.
   ambiguitas, fr. ambiguus: cf. F. ambiguit['e].]
   The quality or state of being ambiguous; doubtfulness or
   uncertainty, particularly as to the signification of
   language, arising from its admitting of more than one
   meaning; an equivocal word or expression.
   [1913 Webster]

         No shadow of ambiguity can rest upon the course to be
         pursued.                                 --I. Taylor.
   [1913 Webster]

         The words are of single signification, without any
         ambiguity.                               --South.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "ambiguity":
   Janus, ambivalence, amphibologism, amphibology, amphiboly,
   antinomy, asymmetry, biformity, bifurcation, cavil, conjugation,
   counterword, dichotomy, disproportion, disproportionateness, dodge,
   double entendre, double meaning, double-talk, doubleness,
   doublethink, doubling, dualism, duality, duplexity, duplication,
   duplicity, equivocacy, equivocal, equivocality, equivocalness,
   equivocation, equivoque, evasion, haggling, hair-splitting,
   halving, hedge, heresy, heterodoxy, heterogeneity, impenetrability,
   imprecision, inapprehensibility, inarticulateness, incognizability,
   incoherence, incommensurability, incompatibility,
   incomprehensibility, inconclusiveness, incongruity, inconsistency,
   inconsonance, indefiniteness, indistinctness, inscrutability,
   irony, irreconcilability, nonconformability, nonconformity,
   numinousness, obscurity, oxymoron, pairing, paradox, polarity,
   polysemant, polysemousness, portmanteau word, pun, quibbling,
   ramblingness, self-contradiction, shift, squinting construction,
   subterfuge, tergiversation, twinning, two-facedness, twoness,
   uncertainty, unconformability, unconformity, unconnectedness,
   unfathomableness, unintelligibility, unknowability, unorthodoxy,
   unsearchableness, vagueness, weasel word