doubtful /ˈdaʊtfəl/adjective 7noun 1forms 4 adjective7 •Subject to, or causing doubt. •Undecided or of uncertain outcome. •Improbable or unlikely. •Experiencing or showing doubt, skeptical. •Suspicious, or of dubious character.Yet it is not the predominant views of the experts but the views of a minority, mostly of rather doubtful standing in their profession, which are taken up and spread by the intellectuals. — 1949 •Unclear or unreliable.The pupils of her great eyes were large in the doubtful lamplight, swallowing their green fires in deep pools of mystery and darkness. — 1922 •(no longer used) Fearsome, dreadful. noun1 •A doubtful person or thing.They had their lists of Liberals and of the doubtfuls who still remained doubtful. As the election drew near, the force of the whole organization was turned upon these unrepentant doubtfuls. — 1976 formsdoubtfuls · doubtfuller · more doubtful · most doubtful