doubt

Noun

• uncertainty about the truth or factuality or existence of something
  • the dubiousness of his claim
    
  • there is no question about the validity of the enterprise
    

• the state of being unsure of something

Verb

• lack confidence in or have doubts about
  • I doubt these reports
    
  • I suspect her true motives
    
  • she distrusts her stepmother
    

• consider unlikely or have doubts about
  • I doubt that she will accept his proposal of marriage
    

Related words

• Synonyms: 
  dubiousness , doubtfulness , question , uncertainty , incertitude , dubiety