This glossary defines nearly 300 terms frequently encountered by stamp collectors and cover collectors. Precise definitions for many philatelic terms do not exist. One collector, dealer or society may define a term in one way, while others will use the term in a slightly different way.
For special uses of some of the terms listed and defined here, contact the appropriate specialist collector group.
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Underprint: A fine printing underlying the design of a stamp, most often used to deter counterfeiting.
Ungummed: A stamp without gum. Ungummed stamps are either stamps issued without gum or an uncanceled gummed stamp that has had its gum soaked off. Many countries in tropical climates have issued stamps without gum.
Unhinged: A stamp without hinge marks, but not necessarily with original gum.
Universal Postal Union: An international organization formed in Bern, Switzerland, in 1874, to regulate and standardize postal usage and to facilitate the movement of mail between member nations. Today, most nations belong to the UPU. (See UPU section of this almanac.)
Unused: An uncanceled stamp that has not been used but has a hinge mark or some other characteristic or defect that keeps it from being considered a mint stamp. Uncanceled stamps without gum may have been used and missed being canceled, or they may have lost their gum by accident.
used: A stamp or stationery item that has been canceled by a postal authority to prevent its reuse on mail. In general, a used stamp is any stamp with a cancel or a precanceled stamp without gum. See also Postally Used and Philatelic Cover.
UPU: Universal Postal Union. An international organization formed in Bern, Switzerland, in 1874, to regulate and standardize postal usage and to facilitate the movement of mail between member nations. Today, most nations belong to the UPU.