Not feeling confident or sure about something; uncertain or skeptical.
From Old French 'doute' and Latin 'dubitare' meaning 'to doubt.' The suffix '-ful' means 'full of,' so the word literally means 'full of doubt.' This formation became common in English during the Middle Ages.
The word 'doubtful' captures something psychologists call healthy skepticism—our brains are actually wired to doubt things as a survival mechanism, which is why humans who question everything tend to make better scientists and detectives than those who accept everything immediately.
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