heedlessness

/ˈhidləsnəs/
noun
  1. The quality or state of not paying attention or being careless; lack of concern for consequences.
    • The accident was a result of the driver's heedlessness.
    • His heedlessness caused him to lose his keys three times in one week.
    • She regretted her heedlessness when she realized she had left the oven on.