noun (n)

• an effort that is inconvenient(noun.act)

  Example:
  Had difficulty walking.
  Finished the test only with great difficulty.
  

  Synonym:
  trouble
  

  source: wordnet30
• a factor causing trouble in achieving a positive result or tending to produce a negative result(noun.cognition)

  source: wordnet30
• a condition or state of affairs almost beyond one's ability to deal with and requiring great effort to bear or overcome(noun.state)

  source: wordnet30
• the quality of being difficult(noun.attribute)

  Example:
  They agreed about the difficulty of the climb.
  

  Synonym:
  difficultness
  Antonym:
  ease, easiness, simpleness, simplicity
  

  source: wordnet30
• The state of being difficult, or hard to do; hardness; arduousness; -- opposed to easiness or facility; as, the difficulty of a task or enterprise; a work of difficulty.(noun)

  source: webster1913