M.M.: Mercantile marine
M/R: Mate's Receipt
M/T: Metric Ton (2204 lbs.)
M/V or M.V.: Motor vessel
Mafi: A generic term for a wheeled trailer used for carrying cargo, also properly known as a roll trailer. It may remain on board throughout ocean passage or be used as a ‘slave’ trailer to transport cargo to and from the vessel once on quay.
Manifest: A list of the goods being transported by a carrier.
Marine Insurance: An insurance which will compensate the owner of goods transported overseas in the event of loss which cannot be legally recovered from the carrier.
Maritime Administration (MARAD): A US government agency, while not actively involved in vessel operation, administers laws for maintenance of merchant marine for the purposes of defense and commerce.
Mark: As used on containers in foreign trade, a symbol or initials shown together with the port of importation and the final destination, if different. Example: A.G. y Cia., Bogota via Barranquilla. Marks are registered at appropriate customs houses; they also appear on bills of lading and invoices. In domestic trade, it is common to mark containers with the name and address of the recipient, but this is rarely done in foreign trade.
Marking: Every article of foreign origin, or its container, imported into the United States shall be permanently marked in a conspicuous place in a manner which would indicate to the ultimate purchaser the English name of the country of origin of the article.
Mate's Receipt: Receipt of cargo by the vessel, signed by the mate (similar to dock receipt).
Measurement Ton: The measurement ton (also known as the cargo ton or freight ton) is a space measurement, usually 40 cubic feet or one cubic meter. The cargo is assessed a certain rate for every 40 cubic feet or 1 cubic meter it occupies.
Megacarrier: One of the predatory massive shipping lines that compete on the largely saturated east/west trades.
MFN (Most Favored Nation): Designation for countries which receive preferential tariff rates. This is no longer the best tariff structure available.
Min. B/L: Minimum bill of lading
MW: Minimum weight factor