Post-mark is a commonly used term in the world of postal services. It refers to the imprint that is put on a letter or package to indicate the date and location it was sent from. However, there are several other terms that can be used interchangeably with post-mark. One of the most popular synonyms for post-mark is cancellation mark, which is used to signify that the post has been canceled or processed. Other synonyms for post-mark include date stamp, mail stamp, and postal mark. All of these terms are used to describe the same process of marking a letter or package to indicate its origin and date of processing.