Synonyms: doubtful, dubious, dubitable, in question
Definition: open to doubt or suspicion
Usage: 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
Similar words: questionable
Definition: subject to question
Usage: questionable motives; a questionable reputation; a fire of questionable origin