A written medical certificate by a doctor stating a diagnosis, condition, and possibly work restrictions; used for sick leave, insurance claims, etc.
会社に提出するために診断書を書いてもらった。
I had a doctor write a medical certificate to submit to my company.
手術後、保険会社に提出するための診断書が必要だ。
After the surgery, a medical certificate is required to submit to the insurance company.
診断書には治療期間と通院の頻度が明記されていた。
The medical certificate clearly stated the treatment period and frequency of visits.