der Patient
patient
A person who receives medical treatment in a doctor's office, hospital, or another facility.
Der Arzt erklärte dem Patienten die Ergebnisse der Untersuchung.
The doctor explained the results of the examination to the patient.

patient
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patient
A person who receives medical treatment in a doctor's office, hospital, or another facility.
Der Arzt erklärte dem Patienten die Ergebnisse der Untersuchung.
The doctor explained the results of the examination to the patient.

'Der Patient' belongs to the N-declension. This means that it takes the ending '-en' in all cases except the nominative singular. Learners often forget this.
Der Arzt spricht mit dem Patienten.
The doctor is talking with the patient.
'Der Patient' in German is only a noun for a person receiving medical treatment. It is not the adjective 'patient' from English. The German adjective for this quality is 'geduldig' (patient).
Du musst geduldig sein, das Lernen braucht Zeit.
You have to be patient; learning takes time.
In a medical context, 'Patient' is often used with certain verbs. Typical examples are: 'einen Patienten behandeln' (to treat a patient), 'einen Patienten untersuchen' (to examine a patient), 'einen Patienten aufnehmen' (to admit a patient), or 'einen Patienten entlassen' (to discharge a patient).
Das Krankenhaus kann heute keine neuen Patienten mehr aufnehmen.
The hospital can't admit any new patients today.
inmate / occupant
'der Patient' and 'der Insasse' can both refer to people in an institution, for example in a clinic. You say 'Patient' when the focus is on medical treatment. You say 'Insasse' when someone is housed in a closed institution, for example in a prison or sometimes in a psychiatric clinic. The words can be confused because a person in a clinic can be both. For normal doctor's offices and hospitals, 'Patient' is the natural word. 'Insasse' sounds more like accommodation, control, or a closed institution.

Der Patient wartet im Behandlungszimmer auf die Ärztin.
The patient is waiting for the doctor in the treatment room.
Der Insasse darf die geschlossene Abteilung nur mit Erlaubnis verlassen.
The inmate may leave the locked ward only with permission.