doubt·ful /ˈdaʊtfəl/
 (a.)可疑的,疑心的,不確的
 Doubt·ful a.
 1. Not settled in opinion; undetermined; wavering; hesitating in belief; also used, metaphorically, of the body when its action is affected by such a state of mind; as, we are doubtful of a fact, or of the propriety of a measure.
 Methinks I should know you, and know this man;
 Yet I am doubtful.   --Shak.
    With doubtful feet and wavering resolution.   --Milton.
 2. Admitting of doubt; not obvious, clear, or certain; questionable; not decided; not easy to be defined, classed, or named; as, a doubtful case, hue, claim, title, species, and the like.
    Beauty is but a vain and doubtful good.   --Shak.
    Is it a great cruelty to expel from our abode the enemy of our peace, or even the doubtful friend [i. e., one as to whose sincerity there may be doubts]?   --Bancroft.
 3. Characterized by ambiguity; dubious; as, a doubtful expression; a doubtful phrase.
 4. Of uncertain issue or event.
    We . . . have sustained one day in doubtful fight.   --Milton.
    The strife between the two principles had been long, fierce, and doubtful.   --Macaulay.
 5. Fearful; apprehensive; suspicious. [Obs.]
 I am doubtful that you have been conjunct
 And bosomed with her.   --Shak.
 Syn: -- Wavering; vacillating; hesitating; undetermined; distrustful; dubious; uncertain; equivocal; ambiguous; problematical; questionable.
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 doubtful
      adj 1: 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: dubious,
              dubitable, in question(p)]
      2: 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: dubious]
      3: unsettled in mind or opinion; "drew a few tentative
         conclusions" [syn: tentative]