I. ˈdau̇tfəl adjective
Etymology: Middle English douteful, from doute doubt + -ful
1. : giving rise to doubt : open to question : not obvious, clear, or certain : not easily defined, classed, or named
a method of investigation whose object is the establishment of truth about doubtful propositions — R.M.Weaver
it is doubtful whether the captain had ever had so much fun — John Steinbeck
2. archaic
a. : giving rise to apprehension : perilous
reported the doubtful and dangerous situation of the empire — Edward Gibbon
b. : full of apprehension : fearful
I hear things which make me doubtful and anxious — Edmund Burke
3.
a. : lacking settled opinion, conviction, or determination : unsure about beliefs, observations, or decisions : wavering, hesitating
even after they had been assured … they looked doubtful — Harold Griffin
some were doubtful how the law would hold — Alfred Tennyson
b. : uncertain in outcome, issue, or result : undecided
were fighting a doubtful battle in which victory was not assured — D.W.Brogan
c. : not certain or easily predictable in regard to political preferences : likely to be carried by either political party
concentrated on winning the electoral votes of the doubtful states
4. : characterized by qualities that impugn and raise often well-founded doubts about worth, honesty, or validity : of uncertain worth or soundness : of equivocal character
the only difference between themselves and others is that they are nice men and the others of very doubtful repute — T.S.Eliot
she wrote rather doubtful grammar — W.M.Thackeray
Synonyms:
dubious , problematical , problematic , questionable : doubtful and dubious indicate uncertainty and indecision in reference to persons or uncertainty, undeterminedness, or unpredictability in reference to events and situations. doubtful simply indicates lack of certainty or conviction; dubious stresses lack of these qualities to somewhat greater degree
she takes me in, telling me there's nobody there. I'm doubtful, but she swears she's alone — Dashiell Hammett
there is the defense of Egypt and the Canal, against greatly superior numbers of the enemy, which six months ago, at all events, looked rather a difficult affair, a doubtful affair — Sir Winston Churchill
the president-elect had expressed the opinion that government, after all, was a pretty simple business. He is now to put that hopeful theory to the test. Friendly counselors thought the prospect more dubious — S.H.Adams
In reference to value judgments, problematical and problematic describe something of the nature of a problem or refer to a situation with a quite unpredictable outcome
at present it is easy to make rash predictions. Publishing is now in a very problematic state — J.T.Farrell
effect of the union endorsement on the labor vote is problematical — New Republic
Often doubtful so strongly questions worth, honesty, or validity that it implies their absence or lack
in very many interpretations where words play no recognizable part, introspection, unless excessively subtle and therefore of doubtful value as evidence, fails to show the imagery is present — C.K.Ogden & I.A.Richards
the builder, on the other hand, who had spent a long life of constant industry, but doubtful honesty, in scraping up a decent fortune — Anthony Trollope
Not so strong, dubious stresses suspicion or mistrust, perhaps well grounded
all sorts of dogmatic standards have been set up by which to measure the degree of a people's civilization … Yet the more carefully we look into the nature of these standards the more dubious they become — Havelock Ellis
millions were stolen outright, and additional millions … poured into dubious railroads and business ventures which rarely repaid ten cents on the dollar — Allan Nevins & H.S.Commager
questionable may mean simply open to question
the detailed study of history should be supplemented by brilliant outlines, even if they contained questionable generalizations — Bertrand Russell
It often describes falsity, unsoundness, or immorality to such a degree that it may be commonly believed in but may be asserted only in guarded statements or hints
the virtues that feed on suffering are very questionable virtues — G.B.Shaw
II. noun
( -s )
: one that is doubtful