Machin: The name given to a well-known series of British definitive stamps first issued in 1967. The design of the stamp depicts a plaster portrait of Queen Elizabeth II created by artist Arnold Machin.
Makeshift booklets: U.S. stamp booklets manufactured using stamps normally issued in individual panes, packaged in generic blue cardboard covers and dispensed by vending machines.
Marcophily: Postmark collecting.
Margin: 1) The selvage surrounding the stamps in a sheet, often carrying inscriptions of various kinds. 2) The unprinted border area around the stamp design. The collectible grades of stamps are determined by the position of the design in relation to the edge of the stamp as perforated or, in the case of imperforate stamps, as cut from the sheet.
Mat: A hard rubber plate used to apply overprints on postage stamps.
Maxim Cards: Post Card with picture showing the same design of the stamp. Stamp should be fixed on the picture side and cancellation should be related to the design on the stamp and card.
Maximaphily: Maximum card collecting.
Maximum card: A picture postcard, a cancel, and a stamp presenting maximum concordance. The stamp is usually affixed to the picture side of the card and is tied by the cancel. Collectors of maximum cards seek to find or create cards with stamp, cancel and picture in maximum agreement, or concordance. The statutes of the International Federation of Philately (FIP) give specific explanatory notes for the postage stamp, the picture postcard, the cancel, concordance of subject, concordance of place and concordance of time.
ME block: U.S. marginal marking block with the selvage bearing the inscription “Mail Early (in the Day).” This first appeared on U.S. marginal selvage in 1968. It was subsequently replaced by the copyright notice. ME blocks typically consist of four or six stamps.
Meter: The mechanical or digital device that creates a valid denominated postage imprint known as a meter stamp. Postage is prepaid to the regulating postal authority. Meters were authorized by the UPU in 1920. They are used today by volume mailers to cut the cost of franking mail.
Microprinting: Extremely small letters or numbers added to the designs of selected United States stamps as a security feature. In most cases, 8-power magnification or greater is needed to read microprinting.
Miniature sheet: A smaller-than-normal pane of stamps issued only in that form or in addition to full panes. A miniature sheet is usually without marginal markings or text saying that the sheet was issued in conjunction with or to commemorate some event. See also Souvenir sheet.
Mint: A stamp in the same state as issued by a post office: unused, undamaged and with full original gum (if issued with gum). Over time, handling, light and atmospheric conditions may affect the mint state of stamps.
Mirror image: An offset negative or reverse impression.
Mission mixture: The lowest grade of stamp mixture, containing unsorted but primarily common stamps on paper, as purchased from missions or other institutions.
Missionaries: The first stamps of Hawaii, issued 1851-52, considered among the great classics of philately.
Mixed postage: The franking on a cover bearing the stamps of two or more stamp-issuing entities, properly used.
Mixture: A large group of stamps, understood to contain duplication. A mixture is said to be unpicked or picked. A picked mixture may have had stamps removed by a collector or dealer.
Mobile Post Office (MPO): Portable mail-handling equipment and personnel, generally in railroad cars, streetcars, trucks or buses.
Mount: Acetate holders, clear on the front and with some sort of adhesive on the back. Collectors use mounts to affix stamps or covers to album or exhibit pages.
Multicolor: More than two colors.
Multiple: An unseparated unit of stamps including at least two stamps, but fewer than the number included in a full pane