Definition of "Referral" :
noun: the act of referring (as forwarding an applicant for employment or referring a matter to an appropriate agency)
noun: a recommendation to consult the (professional) person or group to whom one has been referred
"The insurance company says that you need a written referral from your physician before seeing a specialist."
noun: a person whose case has been referred to a specialist or professional group
"The patient is a referral from Dr. Bones."