doubtful

• doubtfull (archaic)

From Middle English doutfull, douteful, equivalent to doubt +‎ -ful.

• IPA^(key): /ˈdaʊtfəl/

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• Hyphenation: doubt‧ful

doubtful (comparative more doubtful, superlative most doubtful)

1. Subject to, or causing doubt.
2. Experiencing or showing doubt, skeptical.
3. Undecided or of uncertain outcome.
4. (obsolete) Fearsome, dreadful.
5. Improbable or unlikely.
6. Suspicious, or of dubious character.
7. Unclear or unreliable.
   • 1922, E.R. Eddison, The Worm Ouroboros:

     The pupils of her great eyes were large in the doubtful lamplight, swallowing their green fires in deep pools of mystery and darkness.

• doubtfully
• doubtfulness

doubtful (plural doubtfuls)

1. A doubtful person or thing.
   • 1976, Kenneth Gibbons, Donald Cameron Rowat, Political Corruption in Canada: Cases, Causes and Cures, page 45:

     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.