M

M: Military. Scott catalog number prefix to identify stamps other than standard postage
MACHINE POSTMARKS: Cancel applied by a machine vs handstamp and comprises slogan and plain version.
MACHINS: British stamps with a design based on a plaster cast profile of Queen Elizabeth II done by Arnold Machin.
MAIL ART: Labels designed to simulate stamps.
MAIL EARLY: An inscription found in the margins of U.S. stamps and booklet panes. Started in 1965 to encourage people to Mail Early in the Day. These are usually collected in blocks of six.
MAILER'S POSTMARK: Authorized mailer use of a postal cancellation applied prior to mailing.
MAILOMAT: Combination franking and mailing machine introduced by Pitney-Bowes in 1939.
MAJOR VARIETIES: A variation in stamp make-up such as a color change, new paper, watermark, or different perforation.
MALIGAYANG PASKO: Term meaning Happy Holiday on Philippine seals.
MALTESE CROSS: Used as a cancellation during the 1840's on British stamps, and as a watermark.
MANUSCRIPT: Term describing covers or stamps with handwritten postal markings.
MAPLE LEAF: Nickname for Canadian 1897-98 issue depicting Queen Victoria with a maple leaf in each corner.
MARGIN: The portion of unprinted paper that surrounds a stamp or a pane of stamps.
MARGINAL INSCRIPTIONS: Printing that appears in margin of a pane.
MARGINAL RULE: Line in margins around British and commonwealth stamps. Also known as Jubilee Line.
MATCH STAMPS: Revenue stamps used for collecting a match tax.
MAXIMUM CARD: A post card that has an illustration, stamp and cancel all with a common theme.
M B: Auction term meaning Minimum Bid or least amount the auction firm will accept.
M C: Maltese Cross or machine cancel or manuscript cancel
MC: Military Air Post. Scott catalog number prefix to identify stamps other than standard postage.
MCA: Watermarked: Multiple Crown CA
M D: Minor defects
M E: Mail Early post office slogan
ME: Military Special delivery. Scott catalog number prefix to identify stamps other than standard postage.
MEDALLION: A design used as a decoration on commemorative envelopes. Not a postmark.
MEDICINE STAMPS: Revenue stamps used for collecting a medicine tax.
MEM: Memorabilia
M E P S I: Mexico Elmhurst Philatelic Society International
MERRY WIDOW: Term used for the helmet of the Mercury Special Delivery stamp of 1908, since it resembled women's hats of that era.
METALLIC CACHET: Design printed on a very thin sheet of metal and then affixed to a cover.
METER CANCELLATION: A postage fee and cancel applied by a machine to a piece of mail.
MH: Great Britain Machine definitives. Scott catalog number prefix to identify stamps other than standard postage.
M I: Marginal Inscription printing in the margin of stamps or panes.
Mi.: Michel catalog
MICHEL: German language world-wide stamp catalog.
MICHEL CATALOGUE NUMBER: Number assigned to a philatelic item by Michel editors according to that publisher's criteria for such assignment.
MICROPRINTING: Tiny lettering that appears as a message under magnification. Originated as a security device by postal administrations.
MILITARY POSTAL HISTORY: Date stamps and censorship markings of military post offices.
MILITARY STAMPS: Stamps issued for use by a country's military personnel.
MILLIMETER: The thousandth part of a meter, usually abbreviated as "mm."
MINIATURE SHEET: A single stamp or block of stamps with a paper margin on all sides bearing some special wording or design. Some were issued for stamp exhibitions in the U.S.
MINKUS: Minkus catalogue
MINOR VARIETIES: A slight variation in color, a break in the line of the design, or a speck on the stamp can be considered a "minor" variety.
MINT: A stamp as issued by the government printing office with full gum, unhinged and uncanceled.
MIRROR PRINT: Complete or part of a stamp design reversed as if being viewed in a mirror.
MIS: Miniature sheet
MISPERFORATION: Perforations within the design instead of the margins.
MISSION MIXTURE: An assortment of low quality stamps on paper sold by the pound and usually collected by a charitable mission or institution.
MISSIONARIES: Term applied to the rare first issues of Hawaii.
MISSTRIKE: Envelope stamps impressed in the wrong place, partially impressed or doubly printed.
MIXED FRANKING: A properly used cover with stamps of two or more countries or regimes.
MIXED PERFORATION: Stamps that have different perforations on different sides.
MIXTURE: A mixture of stamps, usually on original envelope clippings, containing duplicates. May contain varieties of shades, perforations and minor varieties.
M L H: Mint lightly hinged
MM: Modified Margin
MM: Millimeter
M N H: Mint, never hinged
MODEL: Photographs, artist's sketches, and engraved prints that combine to mock up a proposed stamp design.
MOIRE: Wavy lines printed either on the face or back of a stamp to prevent cleaning and reuse.
MONEY ORDER SERVICE: Some post offices used money order date stamps to cancel mail.
MONEY UNIT: Monetary denomination.
MONSTER: Dutch and Afrikaans word found on stamps of Netherlands and Transvaal indicating "specimen."
MOUNTS: Stamp hinges or cellulose acetate strips used to encase stamps for album mounting.
MOURNING COVER: Cover with a black border.
MOURNING STAMP: Stamps issued for the death of a president, king or other important personage in a nation.
M P O: Mobile Post Office is a vehicular post office that can serve as a temporary postal station.
M P P: Mailer's precancel postmark
MQ: Military Parcel Post. Scott catalog number prefix to identify stamps other than standard postage.
MR: War Tax. Scott catalog number prefix to identify stamps other than standard postage.
M S: Matched set or mint sheet or manuscript
M / S: Miniature Sheet
M T A: Matched Typed Address
MUESTRA: Spanish for "specimen."
M U H: Mint unhinged
MUL: Muller: Catalogue des Aerogrammes du Monde Entier, 1950 (specialized worldwide First Flight Cover Catalog)
MULREADY COVER: Named for designer of Britain's first postal envelope in 1839. The decorated postal stationery was so ridiculed that it had a very short life.
MULTIPLE: A unseparated group of stamps that is less than the full sheet, but more than two.
MULTIPLE CANCELS: Covers with several separate postmarks.
MULTIPLE WATERMARK: Repetition of design and is visible more than once.
MUTE: Term applied to postage stamps or cancellations that do not indicate country or place of origin.
MYLAR: DuPont registered trade name for polyethylene terephthalate film that is colorless, transparent, strong and chemically stable.