noun (n)

• a lack of caution in practical affairs(noun.attribute)

  Antonym:
  prudence
  

  source: wordnet30
• The quality or state of being imprudent; want to caution, circumspection, or a due regard to consequences; indiscretion; inconsideration; rashness; also, an imprudent act; as, he was guilty of an imprudence.(noun)

  source: webster1913