Origin: Latin prefix post-
Postmark has 4 different meanings across 2 categories:
a cancellation mark stamped on mail by postal officials; indicates the post office and date of mailing
A marking made by a postal service on a letter, package, postcard or the like, usually indicating the place where and the date and time when the item was received or processed for the first time, and often serving to cancel a postage stamp.
To apply a postmark on.