doubtful, dubious, dubitable, in question -- (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)
doubtful, dubious -- (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")
doubtful, tentative -- (unsettled in mind or opinion; "drew a few tentative conclusions")
(Sound)
