\Post"mark`\, n.
The mark, or stamp, of a post office on a letter, giving the
place and date of mailing or of arrival.

\Post"mark`\, v. t. [imp. & p. p. {Postmarked}; p. pr.
& vb. n. {Postmarking}.]
To mark with a post-office stamp; as, to postmark a letter or
parcel.