Source : Webster's Revised Unabridged Dictionary (1913)

Dubious \Du"bi*ous\, a. [L. dubius, dubiosus, fr. duo two. See
   {Two}, and cf. {Doubt}.]
   1. Doubtful or not settled in opinion; being in doubt;
      wavering or fluctuating; undetermined. ``Dubious policy.''
      --Sir T. Scott.

            A dubious, agitated state of mind. --Thackeray.

   2. Occasioning doubt; not clear, or obvious; equivocal;
      questionable; doubtful; as, a dubious answer.

            Wiping the dingy shirt with a still more dubious
            pocket handkerchief.                  --Thackeray.

   3. Of uncertain event or issue; as, in dubious battle.

   Syn: Doubtful; doubting; unsettled; undetermined; equivocal;
        uncertain. Cf. {Doubtful}.

Source : WordNet®

dubious
     adj 1: fraught with uncertainty or doubt; "they were doubtful that
            the cord would hold"; "it was doubtful whether she
            would be admitted"; "dubious about agreeing to go"
            [syn: {doubtful}]
     2: open to doubt or suspicion; "the candidate's doubtful past";
        "he has a dubious record indeed"; "what one found
        uncertain the other found dubious or downright false"; "it
        was more than dubitable whether the friend was as
        influential as she thought"- Karen Horney [syn: {doubtful},
         {dubitable}, {in question(p)}]
     3: not convinced; "they admitted the force of my argument but
        remained dubious"