The glossary will help you understand terms and acronyms commonly used in the field of coin collecting, or numismatics.  All entries are listed alphabetically.

• abrasions - Light rubbing or scuffing from friction, not to be confused with hairlines or bag marks.
• adjustment marks - Small striations or file marks found on early United States coins. Made during planchet preparation (before striking) by drawing a file across the planchet to remove excess metal, resulting in a series of parallel grooves. This was done to reduce the planchet to its proper weight.
• alloy - A combination of two or more metals.
• ANA or A.N.A. - The American Numismatic Association, an organization dedicated to numismatic interests.
• ANAAB or A.N.A.A.B. - The American Numismatic Association Authentication Bureau, a third party authentication service operated by the American Numismatic association.
• ANACS or A.N.A.C.S. - The American Numismatic Association Certification Service, a third-party grading service operated by the American Numismatic Association until 1990, when it was sold to Amos Press.
• annealing - The heating and cooling process by which planchets are softened to allow the metal to flow more smoothly during the strike.
• bag mark - A surface mark, usually in the form of a nick, acquired by a coin when it came into contact with others in a mint bag. Bag marks are most common on large and heavy silver and gold coins.
• blemishes - Minor nicks, marks, flaws, or spots of discoloration that mar the surface of a coin.
• bronze - An alloy of copper, zinc, and tin.
• bullion - Uncoined gold or silver in the form of ingots or plate.
• business strike - A coin intended for circulation in the channels of commerce (in contrast to a proof coin specifically struck for collectors).
• choice - An adjective used to describe an especially select specimen of a given grade. For example, Choice AU-55 represents an especially select About Uncirculated coin (typical About Uncirculated being AU-50).
• cleaning - Refers to removing dirt or otherwise altering the appearance of a coin through the use of abrasive materials that mar or scratch the surface in a detectable fashion.
• commemorative - A coin issued to mark a special event or to honor an outstanding person.
• counterstamp - A design, group of letters, or other mark stamped on a coin for special identification or advertising purposes. Counterstamped coins are graded the way regular (uncounterstamped) coins are, but the nature and condition of the counterstamp must also be described.
• DDO or D.D.O. - Doubled Die Obverse, an obverse die which exhibits doubled images in one or more places.
• DDR or D.D.R. - Doubled Die Reverse, a reverse die which exhibits doubled images in one or more places.
• denticles or dentils - The toothlike raised design around the rims of some coins. They are part of the die design.
• designer - The artist who creates a coin's principal devices.
• details - Small features and fine lines in a coin design. Particularly those seen in hair, leaves, wreaths and feathers.
• die - A metal object used to impress a design into a planchet. Dies are usually engraved incuse, so that the devices and inscriptions they produce will be in relief.
• dipping - The act of removing tarnish, surface dirt, or changing the coloration of a coin by applying chemicals, or otherwise artificially treating it with liquids.
• disme - The early spelling of the word "dime," one tenth of a dollar.
• double eagle - A United States twenty dollar gold coin.
• eagle - A United States ten dollar gold coin.
• edge - The area which borders a coin's surface. Also referred to as a coin's "third side." Edges of United States coins may be reeded, lettered or plain.
• electrotype - A counterfeit coin made by the electroplating process.
• engraver - A person who cuts a design into a coinage die.
• field - The portion of a coin's surface not used for a design or inscription.
• fineness - Purity of gold or silver, normally expressed in the terms of one thousand parts.
• grade - The condition or amount of wear that a coin has received. Generally, the less wear a given coin has received, the more valuable it is. Coins are graded on the A.N.A. numerical system from About Good-3 to Perfect Uncirculated-70.
• hairlines - A series of minute lines or scratches, usually visible in the field of a coin, sometimes caused by cleaning or polishing.
• half eagle - A United States five dollar gold coin.
• hub or hob - A metal object with the intended coin design in relief on one end as it would appear on the finished coin. It is used to produce dies.
• incuse - The design of a coin which has been impressed below the coin's surface. When the design is raised above the coin's surface, it is said to be in relief.
• "key date" - Slang usually indicating the rarest (and therefore most expensive) date-and-mint of a particular coin series.
• legend - The principal inscription on a coin.
• lg. - Abbreviation for the word "large," generally referring to a date or mintmark.
• luster - The glossy appearance of the surface of a coin. Although normally brilliant, with time luster may become dull, frosty, spotted or discolored.
• milled edge - A raised rim around the outer surface of a coin. Not to be confused with the reeded or serrated narrow edge of the coin.
• mintmark - A symbol, usually a small letter, used to indicate at which mint a particular coin was struck.
• modification - A minor alteration in the basic design of a coin.
• motto - A word or phrase on a coin.
• mule - A coin struck from obverse and reverse dies not originally intended to be used together.
• NGC or N.G.C. - Numismatic Guaranty Corporation of America, a third-party grading service.
• nick - A small mark on a coin caused by another coin bumping against it or by contact with a rough or sharp object.
• numismatics - Area of study relating to coins, medals, or similar items.
• numismatist - A student or collector of coins, medals, or similar items.
• obverse - The front or fact side of a coin, usually the side with the date or the principal design. Opposite of the reverse side.
• overdate - The date made by superimposing one or more different numbers on a previously dated die.
• oxidation - The formulation of oxides or tarnish on the surface of a coin from exposure to air, dampness, industrial fumes, or other elements.
• pattern - A prototype of a proposed coin design.
• patina - A green or brown surface film found on ancient copper and bronze coins caused by oxidation over a long period of time.
• PCGS or P.C.G.S. - Professional Coin Grading Service, a third party grading service founded in 1986 by David Hall. PCGS was the first third party grading service to sonically seal each coin in a plastic container with its grade and registration number. These plastic containers became popularly referred to as "slabs."
• planchet - Disk on which a design is impressed to make a coin, metal or token.
• proof - Coins struck for collectors and using specially polished or otherwise prepared dies.
• prooflike - Used to describe any uncirculated coin with a mirrorlike reflective surface but lacking the full characteristics of a proof.
• quarter eagle - A United States two and one half dollar gold coin.
• reeded edge - The edge of a coin with grooved lines that run vertically around its perimeter. This type of edge is found on all current United States coins above the five cent denomination.
• relief - Any part of a coin's design that is raised above the coin's surface. When the design has been impressed below the coin's surface, it is said to be incuse.
• restrike - A coin struck from genuine dies at a date later than its original issue.
• reverse - The side of a coin carrying the design of lesser importance. Opposite of the obverse side.
• rim - The raised portion of a coin encircling the obverse and reverse which protects the designs of the coin from wear.
• scratch - A deep line or groove in a coin caused by contact with a sharp or rough object.
• series - One coin of each year issued from each mint of a specific design and denomination, e.g., Standing Liberty Quarters 1916-1930.
• slab - Slang term for a coin that has been graded, registered and encapsulated (sonically sealed) in a plastic container by a third party grading service.
• sm. - Abbreviation for the word "small," generally referring to a date or mintmark.
• striations - Thin, light raised lines on the surface of a coin, caused by excessive polishing of the die.
• striking - Refers to the process by which a coin is minted. Also refers to the sharpness of design details. A sharp strike or strong strike is one with all of the details struck very sharply; a weak strike has the details lightly impressed at the time of coining.
• toning - Natural patination or discoloration of a coin's surface caused by the atmosphere over a long period of time. Toning is often very attractive, and many collectors prefer coins with this feature.
• truncation - The sharply cut off bottom edge of a portrait.
• type - A coin's basic distinguishing design.
• unique - An item of which only one specimen is known to exist.
• variety - A minor change from the basic type design of a coin.
• weak strike - A coin with certain areas of its details (in the areas of high relief) not fully formed because of the hardness of alloy, insufficient striking pressure or improper die spacing.
• wear - The abrasion of metal from a coin's surface caused by normal handling or circulation.
• whizzing - The artificial treatment of a coin by wire brushing, acid dipping, or otherwise removing metal from the coin's surface to give it the artificial appearance of being in a higher grade. Whizzing is an alteration, not a grade or condition.