You can find most popular coin collecting phrases in this coin glossary.
matte proof - matte proof coins are special proofs that have a grainy "sandblasted" look on the surface. Matte proof coins were sometimes made in the early part of the 1900's. Normal proof coins have a mirror like brilliant surface.
medal - an object made of metal that resembles a coin. Often medals are made or given to recognize a person, place, or occasion. Medals have no stated value and are not intended to circulate as money. Sometimes a medal may have intrinsic value (bullion value).
medium of exchange - something accepted by people as having a certain value that is used to exchange or trade. Often coins and paper money are used as mediums of exchange, but it can be anything.
mercury dime - nick name for the US 10 cent pieces made between 1916 and 1945. Although originally called the Winged Liberty Head dime the name "mercury" dime caught on with the public when it was compared to the Roman god "mercury".
milky - describes the appearance on the surface of a coin. Usually a whitish area that is sometimes found on silver coins. The appearance is that of a milk color stain. Sometimes called a milk spot .
milled edge - coin production process that produces the edge of the coin.
mint - place where coins are produced (manufactured). The U.S. Mint produces most coins for the U.S. government in Philadelphia and Denver. Mint facilities in San Francisco and West Point are used to produce some of the Proof and commemorative coins.
mint luster - a frosty, satiny, unique shine found on uncirculated coins
mint mark - a small letter on a coin that identifies which of the U.S. Mints the coin was produced at.
mint restrike – any coin restruck at the mint whose purpose is uncertain of which original strikings from these dies exist. Clearly, most of these are in fact fantasy pieces.
mint set - a complete set of coins produced by a particular mint (contains one of each denomination). Mint sets usually contain "uncirculated" non-proof coins.
mint state - uncirculated
mintage - the number of coins produced (the quantity made for that country, date, mintmark, and type of coin)
Morgan dollar - United States silver dollar made during some of the years 1878 to 1921. Originally called the "Liberty Head" silver dollar. It developed the nickname " Morgan" dollar after the US mint engraver George T. Moran, who designed it.
motto - a saying, phrase, or principle sometimes found on a coin. Example: "In God We Trust", and "E Pluribus Unum"-meaning: Out of many, are one
MS69 - The attribute "MS" is an abbreviation for "mint state". The numbers that follow (in this example 69) indicate the quality of the coin. The quality numbers run from 1 to 70, with a 70 being an absolutely prefect coin. See Coin Grading
mylar - a clear trademark polyester material used to store coins.