noun (n)

• the trait of acting unpredictably and more from whim or caprice than from reason or judgment(noun.attribute)

  Example:
  I despair at the flightiness and whimsicality of my memory.
  

  Synonym:
  arbitrariness, capriciousness, flightiness, whimsey, whimsy
  

  source: wordnet30
• the trait of behaving like an imp(noun.attribute)

  Synonym:
  impishness, mischievousness, puckishness
  

  source: wordnet30
• The quality or state of being whimsical; whimsicalness.(noun)

  source: webster1913