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."