Military. An authorization or document permitting a member of the armed forces to take leave of absence (now usually for a short, specified…

a certificate given to a recruiting sergeant.

a certificate signed by a ship's surgeon entitling a sailor to a payment or pension in compensation for a disability or injury suffered while in…

In plural. The certificates which accompany a military officer's application for permission to resign. Chiefly in to send in one's papers: to resign.