Definition of "doubtful" []

• Subject to or causing doubt: a doubtful claim; doubtful prospects. (adjective)
• Experiencing or showing doubt: Doubtful that the cord would hold, we strengthened it. (adjective)
• Of uncertain outcome; undecided. (adjective)
• Raising doubts as to legitimacy, honesty, or respectability; suspicious: the candidate's doubtful past. See Usage Note at doubt. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "England instead of despotic Russia, it is doubtful if he could work out his discovery of the electrotype -- we say _doubtful_; for, as far as we can learn, it seems hitherto judicially undecided whether the mere use of a patent, not for sale or a lucrative object, is such a use within the statute of James as would be an infringement of a patentee's rights."
• "It all sounds like a bunch of meaningless numbers used to push a candidate whose qualifications still remain doubtful to this day."
• "I remain doubtful that society will ever produce parity enrollment between the genders in science and engineering."