English to English

noun (n)

• doubt about the truth of something(noun.cognition)

  Synonym:
  disbelief, incredulity, mental rejection
  

  source: wordnet30
• the disbelief in any claims of ultimate knowledge(noun.cognition)

  Synonym:
  agnosticism, scepticism
  

  source: wordnet30
• An undecided, inquiring state of mind; doubt; uncertainty.(noun)

  source: webster1913