Difference between Dubious and Questionable

DUBIOUS vs QUESTIONABLE: ADJECTIVE

Open to doubt or suspicion
Fraught with uncertainty or doubt
Fraught with uncertainty or doubt; undecided.
Arousing doubt; doubtful.
Of questionable character.
Doubtful or not settled in opinion; being in doubt; wavering or fluctuating; undetermined.
Occasioning doubt; not clear, or obvious; equivocal; questionable; doubtful.
Not convinced
Arousing doubt; questionable; open to suspicion.
In disbelief; wavering, uncertain, or hesitating in opinion; inclined to doubt; undecided.
Of uncertain event or issue.

Subject to question
Able to be refuted
Open to doubt or challenge; problematic.
Not yet determined or specified.
Of dubious morality or respectability.
Admitting of being questioned; inviting, or seeming to invite, inquiry.
Liable to question; subject to be doubted or called in question; problematical; doubtful; suspicious.
Problematic; open to doubt or challenge
Of dubious respectability or morality

Doubting; hesitating; wavering or fluctuating in opinion, but inclined to doubt.
Doubtful; marked by or occasioning doubt or uncertainty; difficult to determine or relieve of uncertainty; not distinct or plain; puzzling: as, a dubious question; a dubious light.
Of uncertain event or issue: as, a dubious undertaking.
Liable to doubt or suspicion; of doubtful quality or propriety; questionable: as, a man of dubious character; a dubious transaction; his morals or his methods are dubious. Synonyms Unsettled, undetermined.
Doubtful, Ambiguous, etc. (see obscure, a.); questionable, problematical, puzzling.

Liable to question; suspicious; doubtful; uncertain; disputable: as, the deed is of questionable authority; his veracity is questionable.
Capable of being questioned or inquired of; inviting or seeming to invite inquiry or conversation.

Disputable, Iffy, Disreputable, Murky, Debatable, Spurious, Dodgy, Incertain, Dubitable, In question, Unsure, Uncertain, Unconvinced, Doubtful, Questionable

Supposed, Apocryphal, Deniable, Suspect, Refutable, Alleged, Equivocal, Suspicious, Fishy, Problematical, Shady, Problematic, Debatable, Doubtful, Dubious

Disputable, Iffy, Disreputable, Murky, Debatable, Spurious, Dodgy, Incertain, In question, Dubitable, Unsure, Uncertain, Unconvinced, Doubtful, Questionable

Supposed, Apocryphal, Deniable, Suspect, Refutable, Alleged, Equivocal, Suspicious, Fishy, Problematical, Shady, Problematic, Debatable, Doubtful, Dubious

ANT: Thick, turbid, opaque, intransparent, mysterious, dubious, questionable.
Baghdad such remarks become increasingly dubious under closerscrutiny.
Imaginary homelands: the dubious cartographies of Australian identity.
Many free online courses are of dubious quality.
Funny no mention of their dubious business practices?
The recruiter seemed dubious I could do this.
Efficiency is a concept of very dubious value.
So we have to keep this constitutionally dubious doctrine to keep safe a constitutionally dubious authority over certain types of contraband.
Dubious ame and Elusi Dubious Fame and Elusive Foe nutrortune lish queen, Elizabeth, and the Spanish king, Philip II.
In the spiel, dubious arguments against dubious death sentences.

Histopathology should be considered to discern questionable lesions.
Implement procedures for follow up on questionable cases.
Any questionable purchases are reimbursed by the employees.
The value of determining rectal temperature is questionable.
Report: Steph Curry, Kevin Durant questionable tomorrow vs.
Might some of those restrictions be constitutionally questionable?
The evidence behind this dietary strategy is questionable.
Propose removing this verbiage as it is questionable whether this is relevant given the amount of information available and possibly ethically questionable.
Do report coupons you see that look questionable by sending any valuable information you have about where you saw or received a questionable coupon.
We have software on all our electronics that alerts each other if we go to questionable sites or search questionable content, etc.