The state when something (for example, a custom or a law) is no longer observed nor practised; disuse, obsolescence; (countable) an instance of this.
The state of being neglected.
Habitual lack of care.
The act of neglecting.
To fail to do or carry out something due to oversight or carelessness.
To fail to care for or attend to something.
To omit to notice; to forbear to treat with attention or respect; to slight.
To ignore for the sake of simplifying calculations without significantly affecting accuracy.