Stamp issued specifically to prepay postage for mail carried by air.

Look before buying" opportunity where stamps are sent to a collector for examination. Approvals offer the collector a wide range of material to choose from and must be bought or returned to the dealer within a specified time

Stamp collecting terminology for four or more attached stamps forming a square or rectangle.

Small, specifically-printed sheets of stamps sold in a booklet format.

Illustration or description on an envelope denoting the commemorative purpose for which it was mailed.

Stamp collecting term for any mark applied to a stamp to prevent its reuse.

The position of the design on a stamp. On perfectly centered stamps, the design is exactly in the middle.

Stamp produced in a roll for use in vending machines. Usually identified by a pair of straight edges on opposite sides.

Stamp issued specifically to honor a person, place or event; usually on sale for only a short period of time.

A small sheet of stamps bearing a commemorative inscription.

An envelope, postcard or any other wrapper used to mail correspondence.

The cut corner of a postal stationery item (envelope or postcard) bearing the imprinted stamp with ample margins.

Stamp issued for ordinary postal use that remains on sale for an extended period of time.

The monetary value printed on a stamp.

The stamp design is engraved on this small flat piece of soft steel used to print the stamp.

Issued annually since 1934, these U.S. duck hunting permits help finance the federal waterfowl program.

An envelope bearing a postage stamp with raised surface designs printed on the envelope itself.

Stamp collecting terminology for highly-collectible stamps because of something incorrect in their design or manufacture.

Envelope or card postmarked on the affixed stamp's first day of use.

Envelope or card carried on the inaugural mail flight between two points.

Series of small dots embossed on a stamp allowing ink from the postmark to sink in, thus preventing cleaning and reuse of the stamp.

Stamp collecting terminology for the coating of glue on the back of an unused stamp.

Small gummed, glassine strips used to affix stamps to album pages.

Stamp collecting terminology for a stamp bearing straight edges on all four sides.

Stamp with one part of its design upside down in relation to the rest of the stamp.

Stamps in original unused condition, never canceled.

An entire sheet of stamps in original unused condition.

Stamp valid solely for government agency use.

Any printing added to a stamp after the original printing was completed.

Two unseparated stamps joined either vertically or horizontally.

Holes punched between stamps on a sheet to facilitate separation.

Stamp collecting terminology for a device that measures the number of perforations on a stamp per two centimeters.

Technical name for stamp collecting.

Stamp that features a view such as a landscape or seascape, rather than a portrait, coat of arms or other symbolic design.

Four or more attached stamps still fastened to the margin on which the number of the printing plate is inscribed.

Envelopes, cards or other covers bearing imprinted or impressed stamps.

Marking on a postal item recording the date and/or origin of its transit through the mail system.

Stamp collecting terminology for a stamp canceled by the post office before it is sold.

Any stamp that indicates payment of a tax or fee.

The use of slits or cuts between stamps to facilitate separation.

A stamp with a pressure-sensitive adhesive that does not require moistening to affix the stamp to paper.

Stamp collecting terminology for unprinted paper around panes of stamps, sometimes called the margin.

Stamp from which all or part of the sales receipts go to charity or other causes.

Term describing adjoining stamps that differ from each other in design, denomination or some other aspect.

Stamp collecting term for overprint altering or establishing a stamp's face value.

Illustrated or descriptive label attached to a stamp.

Stamp collecting term for metal tweezers used for safe and easy handling of stamps.

A group of stamps with the same theme, such as space travel or Disney cartoons.

A stamp with no cancellation or other sign of use.

A stamp that has been canceled.

Stamp collecting term for design or pattern in paper formed during the manufacturing process, valuable as a security precaution against forgery.

A method of safely determining the existence of a watermark by placing a stamp in a tray filled with special fluid.