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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Dead country: A former stamp-issuing entity that has ceased issuing its own stamps. Also, the old name of an active stamp-issuing entity that has changed its name, so that the old name will no longer be used on stamps.
definitive: Stamp issued in a large indefinite quantity and for an indefinite period, usually several years or more. The United States Presidential issue of 1938 and the 1995 32› Flag Over Porch stamps are examples. Definitive stamp designs usually do not honor a specific time-dated event.
Deltiology: Picture postcard collecting.
Denomination: The face value of a stamp, usually indicated by numerals printed as part of the design. Some modern U.S. stamps produced for rate changes are denominated with a letter. A numerical value is assigned when the letter stamps are issued. An example of this is the H-rate Hat stamp of 1998, which represented the first-class rate of 33›.
Die: The original engraving of a stamp design, usually recess-engraved in reverse on a small flat piece of soft steel. In traditional intaglio printing, a transfer roll is made from a die and printing plates are made from impressions of the transfer roll. When more than one die is used in the production of an issue, distinctive varieties are often identifiable.
Die cut: A form of separation usually employed on self-adhesive stamps. During processing, an edged tool (die) completely penetrates the stamp paper on all sides of the printed stamp, making the removal of the individual stamps from the liner possible. Die cuts may be straight, shaped in wavy lines to simulate perforation teeth, or take other forms.
Directory markings: "Postal indication of failed delivery attempt, stating the reason for failure. Examples are ""No Such Number,'' ""Address Unknown'' and ""Moved.''"
Duck stamp: Popular name for the United States Migratory Bird Hunting and Conservation stamp, issued for use on hunting licenses. Each annual stamp depicts waterfowl. Also used to describe similar issues from the various states for use by hunters or for sale to collectors.
Dummy stamp: Officially produced imitation stamp used to train employees or to test automatic stamp-dispensing machines. Dummy stamps are usually blank or carry special inscriptions, blocks or other distinguishing ornamentation. They are not valid for postage, nor are they intended to reach the hands of stamp collectors. Some do by favor of postal employees.
Duplex cancel: A two-part postal marking consisting of a canceler and a postmark. The canceler voids the stamp so it cannot be reused. The postmark notes the date and place of mailing.
Duplicate: An additional copy of a stamp that one already has in a collection. Beginners often consider stamps to be duplicates that really are not, because they overlook perforation, watermark or color varieties.