Final answer:
Neglect is described in this situation.
Step-by-step explanation:
In this situation, the description that best fits is neglect. Neglect refers to the failure to provide adequate care or attention to a person in one's charge. David, the nurse, left the hospital without leaving anyone in charge of the patient, which resulted in the patient wandering off and falling down the stairs. This constitutes neglect as David failed in his duty to ensure the patient's safety and well-being.