doubtful

(s) 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
dubitable, in question, dubious,
(s) 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
dubious,
(s) unsettled in mind or opinion
- drew a few tentative conclusions
tentative,

dubitable in question dubious tentative

doubtfully doubtfulness