Definition of Negligent Discharge
Negligent discharge is the discharging or firing of a weapon when it is unintended,normally when handling a gun.
Loaded or Unloaded
A Firearm should always be treated as loaded unless proved in a clearing barrel or other safe method , indeed almost all the accidents,fatailites and incidents of a negligent discharge happening are indeed when someone believed their firearms or indeed the firearm they were reached was unloaded.
To ensure this doesnt happen all firearms should be cleared when you pick them up,handle them or indeed place them into or remove from storage.