Accessories: Various products and tools commonly used by the stamp collector, including mounts, stamp tongs, perforation gauges, stock books, hinges and magnifiers. Stamp albums, catalogs and philatelic literature can also be regarded as accessories.
Adhesive: The gum on the back of a stamp or label. Some stamps have been issued with no adhesive.
Aerogram: A postage-paid airletter sheet with gummed flaps that is written on and then folded to form an envelope.
Aerophilately: A specialized area of collecting concentrating on stamps or covers transported by air.
Agency: An extraterritorial post office maintained at various times by a government within the territory of another government.
Air labels: "Air labels, or etiquettes, are used by Universal Postal Union member nations to denote airmail carriage. They are inscribed ""Par Avion'' (French for ""By Airmail''). The text usually includes the same message in the language of the country of origin.
Airmail: The carriage of mail by air.
Albino: An uninked impression made by a printing plate. Such errors are scarce on stamps.
Album: A binder and pages designed for the mounting and display of stamps or covers.
Album weed: In general, a forged stamp.
Approvals: Priced selections of stamps or covers sent to collectors by mail.
Army Post Office: An official United States post office established for use by U.S. military units abroad.
Arrow: On many sheets of stamps, V-shaped arrowlike markings appear in the selvage, generally serving as guides for cutting the sheets into predetermined units.
As is: Indicates that an item or lot is sold without guarantee or return privilege. Stamps are usually sold ""as is'' when they are damaged or are possibly not genuine."
Authentication mark: A marking, such as initials, placed on the reverse of a stamp examined and certified to be genuine by an expert.
APO: Army Post Office.