From Longman Dictionary of Contemporary Englishmedical certificateˈmedical cerˌtificate noun [countable] BECMNan official piece of paper signed by a doctor saying that you are too ill to work or that you are completely healthy → sick note
Examples from the Corpus
medical certificate• If you're sick you have to get a medical certificate.• She even had a medical certificate to prove she was clean.• If a member of staff is sick for more than 7 days they must provide a medical certificate.• Remember, if you are sick for a second week, we shall require a medical certificate.• Where the witness is ill it is advisable to send a medical certificate with the notice itself.• Pilots over age 40 must renew the medical certificate required as a condition of licensing every two years.From Longman Business Dictionarymedical certificateˈmedical cerˌtificate a document signed by a doctor, stating that a person is not able to work for medical reasonsFor absences of more than three days, a medical certificate is required. → certificate 