WordNet (r) 3.0 (2006):

iffy
    adj 1: subject to accident or chance or change; "a chancy appeal
           at best"; "getting that job was definitely fluky"; "a
           fluky wind"; "an iffy proposition" [syn: chancy,
           fluky, flukey, iffy]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "iffy":
   accidental, adventitious, aleatory, arguable, at issue, capricious,
   casual, causeless, chance, chancy, confutable, conjectural,
   contestable, contingent, controversial, controvertible, debatable,
   deniable, destinal, dicey, disputable, doubtable, doubtful,
   dubious, dubitable, erratic, fatal, fatidic, fluctuant, fluky,
   fortuitous, in dispute, in doubt, in dubio, in question,
   incalculable, incidental, indeterminate, mistakable, moot,
   open to doubt, open to question, problematic, questionable,
   refutable, risky, speculative, suppositional, suspect, suspicious,
   uncaused, undetermined, unexpected, unforeseeable, unforeseen,
   unlooked-for, unpredictable, whimsical