Questionable; doubtful (13)
I believe the answer is:
problematical
I believe this is a double definition.
'questionable' is the first definition.
(similar in meaning)
'doubtful' is the second definition.
(thesaurus)
(Other definitions for problematical that I've seen before include "Difficult; doubtful" , "Open to doubt or debate" , "Presenting difficulties" , "Dubious" .)