Final answer:
The best term for an outpatient facility that doesn't offer overnight stays is an outpatient clinic or center, where patients receive care and return home the same day.
Step-by-step explanation:
The term that best defines an outpatient facility not offering overnight hospitalization is simply an outpatient clinic or center. These facilities provide medical treatment and diagnostic services to patients who visit for treatment during the day and return home the same day without the need for overnight hospital stay. Studies, such as the one by Stensland, Watson, and Grazier (2012), primarily focus on inpatient psychiatric treatment and the associated costs, but it's important to distinguish that an outpatient setting is different as it does not involve extended hospital stays.