What is "underprint"

n. (context philately English) A stamp with a logo or company initials printed on the underside of the stamp, intended to prevent unauthorised use of the stamp or as a form of advertising.

An underprint is anything printed underneath the main design of a stamp, banknote or similar item. Underprinting is used as a security measure to prevent forgery, or the cleaning of a postmark from a used stamp. The most common form of underprinting is burelage which takes the form of a feint pattern of lines or dots. Underprinting may also take the form of single or repeating words, for instance the word CUSTOMS at one time appeared underprinted on British revenue stamps.

In ichnology, underprints (also known as transmitted prints or ghost prints) are fossil footprints that are preserved in a sedimentary level beneath that which was directly imprinted upon by the foot of the trackmaker. The concept goes all the way back to the 1858 ichnological research of the Reverend Edward Hitchcock performed on the Newark Basin dinosaur tracks. Because underprints are produced indirectly they can only preserve the basic anatomy of the trackmaker's foot, whereas true tracks can preserve fine details skin impressions in favorable circumstances.