Packet: An envelope or package of stamps, offered for sale by a dealer.  A packet generally refers to a package with no duplicates.

Packet Cancellation: A special postmark applied to mail carried on a ship chartered or owned by a government or post office.

Pair: Two unseparated stamps. Can be either a vertical or horizontal pair.

Pane: One of usually four or six groupings of stamps which go to make up a full sheet.  Commonly referred to, (in error) as a sheet.

Parcel Post: A class of postal services reserved for the sending of packages or parcels no longer in use in the United States.

Patriotic Covers: Covers on which patriotic pictures and/or slogans appear.  They were very common during "The American Civil War."

Perfins: Holes punched in a stamp to form letters of a design, used to advertise or to prevent theft.

Perforation Size: The number of perforated holes in a space 2 centimeters long as determined by use of a perforation gauge.

Permit: A license to use a registered permit number, given to the sender of bulk mailings to speed up the mailing process.

Philatelic Agency:  Any bureau or central point maintained by a government for selling current issues of stamps in quantity to dealers and in some cases to collectors.

Photogravure: A method for printing stamps, in which a photograph of the stamp design is etched into a metal plate, usually for use on a rotary press.

Pictorials: Stamps bearing pictures of landscapes, animals, flowers, etc. as differentiated from those with portraits and/or symbols.

Plate Number: A file or index number engraved in a plate from which stamps are printed used to keep track of the plates. Usually found in one of the corner margins.

Plate Number Block: A block of stamps with the attached portion of the sheet margin bearing the plate number.

Plate Number Coil: (PNC) A strip of three or five coil stamps containing the plate number below the center stamp.

Position Block: A block of four or more stamps with markings indicating a position on the sheet such as arrow blocks.

Postage and Revenue: An inscription on a stamp  indicating that they can be used for either postage or revenue purposes.

Postage Due Stamps: Special stamps  affixed to mail to indicate that the postage was underpaid by the sender. the amount indicated by the Postage Due stamp is collected from the addressee. Postage Due stamps are no longer in use.

Postal Stationery: Envelopes, postcards, wrappers, etc., with stamps officially printed or embossed on them.

Postally Used: Used to indicate a stamp which was actually used as postage as distinguished from a stamp that was "Canceled To Order" or used for other non-mail purposes.

Postmaster's Provisional:  A stamp issued by individual postmasters in various towns and cities used locally before general postal issues were made available.  Used in the United States during 1846 and again by Confederate Postmasters during 1861.

Quadrille Paper: Paper containing intersecting vertical and horizontal lines forming small squares or rectangles.

Redrawn: A stamp design that retains all the main characteristics and essential elements of its type, but contains minor variations.

Registered Mail: Mail for which the sender is given a numbered receipt by the post office, assigning a specific monetary value to the item being mailed for the purpose of compensation for in case of a loss.

Reissue: A stamp which has been withdrawn from circulation and reprinted and reissued at a later date by postal authorities.

Reprint: A stamp printed from the original plates, usually after an issues has become obsolete, and not intended for postal use.

Revenue Stamps: Stamps affixed to documents, spirits, stock certificates, playing cards, tobacco, etc. to show that the required government tax has been paid.

Rotary Press: A printing method using curved plates. Stamps that have been printed on this type of press are slightly higher or wider than those printed on a flat-bed press.

Rouletteting: A method of stamp separation in which slits or pin holes of various sizes and shapes are made between the rows and columns of stamps without removing any paper as is done with perforations.

Security Paper: A special paper used to make it more difficult to produce fraudulent  stamps or alterations.

Se-tenant: A term applied to two or more unseparated stamps having different designs and/or values. The stamps are usually part of a set of commemorative stamps.

Secret Marks: Microscopic or hidden marks placed in a stamp design by the engraver for identification purposes.

Semi-Postal Stamps: Stamps that have been surcharged, overprinted or inscribed with an extra charge in addition to the postage fee in order to obtain funs for various charities.

Series: All the denominations of stamps belonging to a certain issue, as in the "Transportation Series."

Short Set: A group of stamps from a particular issue or series minus the high values of the set.

Soaking: The process of immersing a stamp in water to remove any attached bits of paper.

Souvenir Sheet: A (pane) of one or more stamps specifically printed by a government for a specific event or purpose. The Margins usually contain an inscription describing the purpose of the issue.

Space filler: An inferior copy of a stamp used to fill an album space until a better copy can be obtained.

Special Delivery Stamp: A stamp used to indicate that the postal item is to be delivered by special messenger to the addressee upon its arrival at the Post Office.

Specialist: A collector who restricts his stamp collecting to a special field or area. Examples of a specialist collection could be United States Revenues, Confederate Issues, Ships on Stamps, Stampless covers, Duck Stamps, etc.

Stampless Covers: Envelopes or sheets folded into envelopes with the written message on the inside. which were posted prior to the use of postage stamps. The covers usually bear postal markings indicating the date the item was mailed and its Postal Origin.  In addition, other markings such as Paid, Ship, Steamboat, Way, etc. may be found on both stampless and stamped covers.  These additional markings greatly enhance the value of the cover.

Straight Edge: A stamp with one or two adjacent sides without perforations, caused by cutting the sheet into panes.

Surcharge: An overprinted revaluation of a stamp, which can also include blocking out the original denomination.

Teeth: The projections between perforation holes on a stamp.

Telegraph Stamps: Stamps used to pay telegraph charges or tolls.

Tete-Beche: A pair of unseparated stamps arranged so that one is printed upside-down in relation to the other. Triangle stamps are usually printed in this manner.

Tied to: Indicates the stamp has been affixed to an envelope card or wrapper with a postmark extending over the stamp and onto the cover authenticating that the stamp and cover belong together.

Topical Collecting: The practice of collecting only stamps relating to a single subject or theme, such as, Ships, Seashells, Birds or Trains.

Town Cancellation: The most common type of postmark giving the name of the post office were the item was mailed from and usually the date.

Ultraviolet Lamp: A lamp producing strong ultraviolet rays used by experts to check for tampering, aniline inks or phosphor tagging on postage stamps.  Both Short-wave and Long-wave Ultraviolet lamps are  used in Stamp collecting; depending on the Country of issue and the type of tagging used.

Universal Postal Union: (UPU) An international organization formed in 1874, which virtually all countries are members of.  The purpose of the UPU is to regulate international postal matters and facilitate cooperation among its members on such issues as international mail distribution and postal rates.

Unused: Not canceled or otherwise defaced, but not in mint condition or with original gum.

Used: The term denotes a stamp that has been postally used rather than canceled to order.

Vignette: The main portion of a stamp design, usually the portrait or picture inside the border.

Wallpaper: A disparaging term used to describe stamps which have little or no Philatelic value.

Want List: A list of some or all of the stamps a collector is missing from his collection.  A want list is usually presented to a dealer by the collector, specifying the stamps needed and listing their catalog number, desired condition and quantity needed.  A suggested price range is also sometimes submitted.

War Tax Stamp: Stamps issued in wartime for some countries, required to be used on mail in addition to regular postage, to help defray the expenses of the war.

Watermark: A design consisting of characters, letters, numbers, words, Or sometimes (unintentionally) caused by a plate flaw, impressed into the paper during its manufacture and visible in part or whole on each stamp printed on the paper.  The design can sometimes be seen by holding the stamp up to a light. The normal method for detecting watermarks is with the aid of special watermark detecting fluid and a small plastic tray.

Wove Paper: The most commonly used paper for the printing of stamps.  It has a finely netted texture created during the paper's manufacture.

Wrapper: A sheet of paper, gummed at one end and printed with a stamp, to be used for wrapping and mailing periodicals.

Zeppelins: Stamps issued for use on the German Airship Graf Zeppelin.

Zip-Code Inscription Block: A block of U.S. stamps containing the sheet margin inscription, "Use Zip Code."