Carelessness
Part of speech: noun
Definition: Lack of care.
Example sentence: Spaceflight will never tolerate carelessness, incapacity, and neglect.
Negligence
Part of speech: noun
Definition: The state of being negligentThe tort whereby a duty of reasonable care was breached, causing damage: any conduct short of intentional or reckless action that falls below the legal standard for preventing unreasonable injury.The breach of a duty of care: the failure to exercise a standard of care that a reasonable person would have in a similar situation.
Example sentence: If we're serious about our kids having a livable world, building fossil fuel infrastructure in 2018 is a sign of deep negligence, which is the kindest thing I can say about it.