Acidification: The addition of acid (usually tartaric) during fermentation, frequently necessary in hot climates where grapes tend to over ripen and become deficient in acidity, thereby losing freshness.

Acidity: The acids in a wine (principally tartaric, malic, citric and lactic) provide liveliness, longevity and balance.

Barrique: The standard Bordeaux barrel, holding 225 liters or the equivalent of about 300 bottles of wine.

Blanc de Blanc: "White of Whites", meaning a white wine made of white grapes, such as Champagne made of Chardonnay.

Blanc de Noirs: White wine made of red or black grapes, where the juice is squeezed from the grapes and fermented without skin contact. These wines can have a pale pink hue.

Botrytis Cinerea: Called the "Noble Rot". A beneficial and often highly desirable mold or fungus that attacks grapes under certain climatic conditions and causes them to shrivel, deeply concentrating the flavors, sugar, and acid.

Brettanomyces: A wild yeast strain that occurs naturally in wineries and vineyards. Low levels of infection can add complexity to a wine. High levels are perceived by most as a fault.

Brut: A general term used to designate a relatively dry-finished Champagne or sparkling wine, often the driest wine made by the producer.

Carbonic Maceration: A form of anaerobic fermentation, practiced extensively in Beaujolais that produces a bright, fruity style of wine.

CÈpage: The finished blend, e.g. Cabernet/Merlot; Syrah/Grenache.

Chaptalization: The addition of sugar during fermentation to increase a wine's alcoholic strength.

CuvÈe: A blend or special lot of wine.

Demi-Sec: In the language of Champagne, a term relating to sweetness; although demi-sec means half-dry, demi-sec sparkling wines are usually slightly sweet to medium sweet.

Dry: Opposite of sweet; having no perceptible taste of sugar.

Ester: Volatile flavor compound naturally created in fermentation. Often fruity, flowery, or spicy.

Extra Dry: A common Champagne term not to be taken literally. Most "extra-dry" Champagnes are sweet.

Fermentation: The conversion of grape juice into wine through the action of yeasts present in the juice, or added to the juice, which turn sugar into alcohol. This alcoholic fermentation is also known as primary fermentation.

Fining: A method of clarifying wine by pouring a coagulant (such as egg whites) on top and letting it settle to the bottom. In general, a fining agent is allowed to fall through the wine, while in filtration; the wine is passed through a filter.

Fortify: To raise the alcohol content of a wine by the addition of brandy or neutral spirits.

Lees: Solid residue (mostly dead yeast cells) and grape pulp, pips, and skins, (known as gross lees) that remains in the cask after the wine has finished fermentation. Many white wines and some reds are kept on their lees for a period of time to protect them from oxidation, enrich their textures, and add complexity.

Malolactic Fermentation: A secondary fermentation in which the more tart malic acid is converted into softer lactic acid and carbon dioxide. Malolactic fermentation, which generally follows the alcoholic fermentation, is nearly always carried out in red wines. Some producers of white wines encourage malolactic fermentation, while others, especially those in hot regions that produce grapes with low levels of acidity, avoid it in order to retain the wine's freshness.

MÈthode Champenoise: The process whereby wine undergoes a secondary fermentation inside the bottle, creating bubbles.

Must: Grape juice not yet fermented or in the process of being fermented into wine.

Nouveau: A style of light, fruity, youthful red wine bottled and sold as soon as possible. Applies mostly to Beaujolais.

Oaky: Smell or taste of the oak cask in which the wine was vinified and/or aged; oak notes can include such elements as vanilla, clove, cinnamon, cedar, smoke, toast, bourbon, and coffee.

Rack: To transfer wine from one vessel to another, leaving the sediment behind.

Reduced/Reductive: Essentially the opposite of oxidized or oxidative. Instead of forming bonds with oxygen, aromatic compounds in the maturing wine form bonds with hydrogen and sulfur. This generally occurs during barrel or tank ageing.

Solera: A system used in the fractional blending of wines of various ages in order to achieve a consistent product. Most widely found in Jerez (Sherry).

Sulfur: The most common disinfectant and preservative for wine. Most winemakers feel that it is nearly impossible to produce stable wine without judicious use of sulfur products at one or more stages of vinification.

Tannin: A bitter, mouth-drying substance found in the skins, stalks and pips of the grapes--as well as in wood barrels. Tannin acts as a preservative and is thus an important component if the wine is to be aged over a long period. Tannins are frequently harsh in a young wine, but gradually soften or dissipate as the wine ages in the bottle.

Volatile Acidity (VA): Vinegar. In very small quantities this can add a refreshing zing to a wine. In excessive amounts it is perceived as a fault.

Yeast: The various microorganisms that cause fermentation. Wild yeasts are naturally present on grape skins, but cultivated yeasts are generally used to control fermentation more carefully.

Balance: The relative proportions of fruit, acid and sugar (if any) in a wine. May also include alcohol.

Corked, Corky: Contaminated by a tainted cork, which gives the wine a musty, wet cardboard smell.

Filtration: A method of clarifying and stabilizing wine to give it a pleasingly lucid color and to remove yeasts, bacteria or other solid matter that might otherwise spoil the wine after it has been bottled. Excessive filtration, like excessive fining, can strip a wine of aroma, body, texture and length.