1. • noun - the state of being unsure of something
   • noun - uncertainty about the truth or factuality or existence of something
   • verb - consider unlikely or have doubts about
   • verb - lack confidence in or have doubts about
2. • To be undecided or skeptical about: began to doubt some accepted doctrines.
   • To tend to disbelieve; distrust: doubts politicians when they make sweeping statements.
   • To regard as unlikely: I doubt that we’ll arrive on time.
   • To suspect; fear.
   • A lack of certainty that often leads to irresolution.
   • A lack of trust.
   • A point about which one is uncertain or skeptical: reassured me by answering my doubts.
   • The condition of being unsettled or unresolved: an outcome still in doubt.
   • Certainly.
   • The choice among these three is partly guided by the intended meaning of the sentence but is not cast in stone.
3. • v - to be uncertain about

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