Maceration
The contact of grape skins with the must during fermentation, extracting phenolic compounds including tannins, anthocyanins, and aroma.

Madeirized
A wine showing Madeira-like flavour, generally evidence of oxidation. Sometimes used to describe white wine that has been kept long past its prime.

Magnum
A bottle holding 1.5 litres, the equivalent of two regular wine bottles.

Malolactic fermentation
Also known as malo or MLF, a secondary fermentation in wines by lactic acid bacteria during which tart tasting malic acid is converted to softer tasting lactic acid.

Marc
French for "fruit skins". See "pomace".

Master of Wine
A qualification (not an academic degree) conferred by The Institute of Masters of Wine, which is located in the United Kingdom.

May wine
A light German wine flavored with sweet woodruff in addition to strawberries or other fruit.

Maynard A. Amerine
Maynard A. Amerine (1911-1998) A professor emeritus at the University of California, Davis, and world renowned authority on wine. His research on the technical aspects of grape growing and wine making invigorated the California wine industry as it recovered from Prohibition. His work is considered by many to be the cornerstone for the industry's success in the world wine community.

Mead
A wine-like alcoholic beverage made of fermented honey and water rather than grape juice.

Merlot
Merlot is a variety of wine grape used to create a popular red wine.

Méthode Champenoise
Méthode Champenoise

Méthode Champenoise
A large bottle holding six litres, the equivalent of eight regular wine bottles.

Microoxygenation
The controlled exposure of wine to small amounts of oxygen in the attempt to reduce the length of time required for maturation.

Midpalate
A tasting term for the feel and taste of a wine when held in the mouth.

Millerandage
A French term referring to a viticultural problem in which grape bunches contain berries of greatly differing size and levels of maturity. Caused by cool weather during flowering.

Mis en bouteille au château
French for "bottled at the winery," usually in Bordeaux.

Mud
See "Lees".

Mulled wine
Wine that is spiced, heated, and served as a punch.

Must
Unfermented grape juice, including pips, skins and stalks.

Must weight
The level of fermentable sugars in the must and the resultant alcohol content if all the sugar was converted to ethanol.