Real Dictionary

outpatient
An outpatient is someone who receives treatment at a hospital but does not spend the night there.

outpatient in American English
a patient who is treated at a hospital, clinic, etc. and leaves without becoming an inpatient
noun: a patient who receives treatment at a hospital, as in an emergency room or clinic, but is not hospitalized

outpatient in British English
noun: a nonresident hospital patient

outpatient in Insurance
noun: An outpatient is someone who goes to a hospital for treatment but does not stay overnight.