DOUBTFUL
doubtful, dubious
(adjective) 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”
doubtful, dubious, dubitable, in question
(adjective) 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
doubtful, tentative
(adjective) unsettled in mind or opinion; “drew a few tentative conclusions”
Source: WordNet® 3.1
Etymology
Adjective
doubtful (comparative more doubtful, superlative most doubtful)
Subject to, or causing doubt.
Experiencing or showing doubt, sceptical.
Undecided or of uncertain outcome.
(obsolete) Fearsome, dreadful.
Improbable or unlikely.
Suspicious, or of dubious character.
Unclear or unreliable.
Noun
doubtful (plural doubtfuls)
A doubtful person or thing.
Source: Wiktionary
Doubt"ful, a.
1. Not settled in opinion; undetermined; wavering; hesitating in
belief; also used, metaphorically, of the body when its action is
affected by such a state of mind; as, we are doubtful of a fact, or
of the propriety of a measure.
Methinks I should know you, and know this man; Yet I am doubtful.
Shak.
With doubtful feet and wavering resolution. Milton.
2. Admitting of doubt; not obvious, clear, or certain; questionable;
not decided; not easy to be defined, classed, or named; as, a
doubtful case, hue, claim, title, species, and the like.
Beauty is but a vain and doubtful good. Shak.
Is it a great cruelty to expel from our abode the enemy of our peace,
or even the doubtful friend [i. e., one as to whose sincerity there
may be doubts] Bancroft.
3. Characterized by ambiguity; dubious; as, a doubtful expression; a
doubtful phrase.
4. Of uncertain issue or event.
We . . . have sustained one day in doubtful fight. Milton.
The strife between the two principles had been long, fierce, and
doubtful. Macaulay.
5. Fearful; apprehensive; suspicious. [Obs.]
I am doubtful that you have been conjunct And bosomed with her. Shak.
Syn.
– Wavering; vacillating; hesitating; undetermined; distrustful;
dubious; uncertain; equivocal; ambiguous; problematical;
questionable.
Source: Webster’s Unabridged Dictionary 1913 Edition