Journal Stamps: Stamps used to pay bulk postage and tax on newspapers, magazines and other periodicals.

Jubilee: A Silver (25th), Golden (50th) or Diamond (60th) anniversary of a rulers reign.  Most notably Stamps of Great Britain and the Commonwealth nations.

Killer Cancellation: A cancellation which is very heavy and covers most of the stamp effectively obliterating the design.
Note: Some Killers are highly collectable as "Fancy Cancels."

Laid Paper: One of the two principal types of paper used for printing stamps. Made up of closely parallel horizontal and/or vertical lines created during the paper's manufacture.

Letterpress: (Typography) The Stamp design or a photograph of it is transferred onto a metal plate with a greasy ink and the rest of the plate is etched away leaving only the raised design.  Letterpress stamps can be detected by the impression of the design standing out on the back.

Letter-sheet: A sheet of writing paper with a stamp already printed on it so that the sheet can be folded, addressed and mailed without  having to use a separate envelope.

Line Pair: A pair of stamps showing a line of color between them.

Lithography: A flat surface printing method in which the design is drawn, photographed or otherwise transferred to a stone or metal plate and fixed in place using a treatment with acid to accept a greasy ink, while the rest of the plate is kept damp to reject the ink.  Lithographed stamps are distinguished by their generally flat surface.

Local Stamps: Stamps issued for use only in a certain city, town or district and not valid for postage anywhere else.

Luminescent Stamps: (Phosphor Tagged) Stamps treated with a phosphorescent substance or printed on fluorescent paper, or with fluorescent ink for use with electronic processing  machines.

Major Varieties:  Usually refers to stamps of the same issue that differ in one or more major areas; design, color, denomination, shape, size, paper, perforations, watermarks, inscriptions, or imprints. Can also refer to stamps of different issues.

Manuscript cancellation: A cancellation done by hand with either a pen or pencil.

Margin: The unprinted paper surrounding the design of a stamp.

Maximum Card: A pictorial postcard showing the stamp design or other subject bearing either the stamp pictured or a stamp related to the design and bearing a postmark related to the stamp or subject.

Meter Cancellation: A design printed directly on an envelope or strip of gummed paper by a postage meter machine and used in place of postage stamps.

Millimeter: (mm) A unit of measurement in the metric system, equal to a tenth of a centimeter. The most commonly used unit of measurement in stamp collecting. for both stamp dimensions and in measuring perforation spacing.

Miniature Sheet: Usually refers to a Souvenir sheet that is of a smaller size than a regular Pane of stamps.
Note: What is most commonly referred to as a sheet is actually a Pane of Stamps - usually one of four or six that make up a Full sheet.

Mint condition: A stamp that is "Post Office Fresh," that is in the same condition as when it left the mint or printing source. A stamp which has never been soiled, stained, creased, marked, or torn. Usually with Full Original Gum, (See Below).

Mint Never Hinged: A stamp which has full original gum and has never been hinged soiled stained creased marked or torn.

Mission Mixture:  Mixed stamps, sometimes still on paper that has been collected by mission homes and other charitable organizations.  The Term has evolved to signify any bulk mixture of unsorted stamps.

Multiple: A group of stamps from the same sheet, unseparated, numbering greater than two but less than a full pane.

Name Block: A block of stamps on which a name appears in the margin rather than a number.

New Issue: Refers to the latest stamp or stamps currently issued by a country.

Occupation Stamps: Stamps issued by a country for use in the occupied territory of another country.

Off Paper Mixture: A term used to refer to a package of stamps which have been removed from the paper to which they were originally affixed.

Official Stamps:  Stamps that are used by a country for use on Official Government correspondence.

Offset Lithography: A type of printing in which the design is first transferred from the printing plate to a rubber roller, then from the roller to the paper.

On Cover: A stamp which is still attached to the entire piece of mail, generally an envelope on which it was originally affixed.

Original Gum: (O.G.) The unaltered gum with which the stamp was originally issued.

Overprint: Any additional printing added to a stamp after the stamp itself has been printed.

Oxidation: The chemical process by which the original color of the stamp changes through exposure to the elements.