The Collaborative International Dictionary of English v.0.48:

Irresolution \Ir*res`o*lu"tion\, n. [Cf. F. irr['e]solution.]
   Lack of resolution; lack of decision in purpose; a
   fluctuation of mind, as in doubt, or between hope and fear;
   irresoluteness; indecision; vacillation.
   [1913 Webster]

         Irresolution on the schemes of life which offer
         themselves to our choice, and inconstancy in pursuing
         them, are the greatest causes of all unhappiness.
                                                  --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

irresolution
    n 1: doubt concerning two or more possible alternatives or
         courses of action; "his indecision was only momentary but
         the opportunity was lost" [syn: indecision,
         indecisiveness, irresolution]
    2: the trait of being irresolute; lacking firmness of purpose
       [syn: irresoluteness, irresolution] [ant: firmness,
       firmness of purpose, resoluteness, resolution,
       resolve]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "irresolution":
   amiable weakness, breakability, brittleness, capriciousness,
   chance, chanciness, changeableness, collapse, daintiness, delicacy,
   destructibility, disintegration, effeminacy, erraticism,
   erraticness, fickleness, flimsiness, fragility, frailty,
   frangibility, hesitancy, hesitation, human frailty,
   incalculability, incertitude, indecision, indecisiveness,
   indemonstrability, indeterminacy, indetermination, indeterminism,
   infirmity of will, inherent vice, lightness, luck, moral weakness,
   randomness, shilly-shally, sleaziness, slightness, suspense,
   suspensefulness, to-and-fro, unaccountability, uncertainness,
   uncertainty, uncertainty principle, undecidedness,
   undeterminedness, unforeseeableness, unpredictability,
   unprovability, unsubstantiality, unsureness, unverifiability,
   vacillation, velleity, wavering, whimsicality, wispiness,
   womanishness