noun
train delay certificate; certificate of lateness
A document issued by a railway company or other transport operator to certify that a service was delayed, often used to excuse lateness to work or school.
電車が遅れたので、駅で遅延証明書をもらった。
Because the train was late, I got a delay certificate at the station.
Compound of 遅延 (delay) + 証明書 (certificate).