Lactic acid
One of the many acids that contribute to the overall acidity of a wine. This acid, which is also found in milk, makes a much softer impression on the palate than many others, such as malic acid. As a consequence many winemakers encourage the conversion of the harsh malic acid to lactic acid by the malolactic fermentation.

Lagar (Portugal, Spain)
Not a misspelling of a popular style of beer, rather a traditional stone trough where grapes are crushed underfoot.

Landwein (Germany, Austria)
The equivalent of French vin de pays, although whereas there are many enjoyable bottles of vin de pays, this is less likely to be true of landwein!

Late bottled vintage
A style of Port, first introduced by Quinta do Noval in 1954. It is designed to mimic the vintage style, with less time until release and less expense. The wines are softened by ageing in wood for up to six years and are generally ready for consumption when released. The best, although not the cheapest, examples are labelled 'traditional' or 'unfiltered'. These offer a real glimpse of vintage quality and often continue to improve after release.

Late Harvest
Produces grapes that are riper and sweeter. This makes sweet, dessert-style wines.

Leafy
Describes wines that smell like leaves and sometimes herbs. A hint of this can add to the complexity of the wine, however a strong whiff of it is unpleasant and vegetal.

Lees
A heavy sediment consisting of dead yeast cells and other solid matter such as grape pulp, seeds and other grape particles.

Left Bank
A collective term for the communes of the left bank of the Gironde in Bordeaux.

Legs
The rivulets of wine that slowly glide down the glass after swirling the wine are often called legs or tears. They’re related to surface tension differences between water and alcohol. Contrary to popular belief, these aren't related to the compound glycerine in wine. The more alcoholic the wine, the slower the legs go down the glass and the more defined they are. This doesn’t indicate a better wine, just a more alcoholic one.

Length
How long the flavor of the wine persists on the palate after it has been swallowed. This is also called the finish.

Lieu-dit (France)
A term most often used when describing Burgundy and Alsace. It refers to a named vineyard which does not have Premier or Grand Cru appellation.

Light
Wines light in alcohol but also in texture and weight. It also describes how the wine feels in the mouth.

Lively
Describes a fresh, young, thirst-quenching wine with crisp acidity. Don’t be afraid of acidity: it is to wine what salt is to food in that it brings the flavor forward. Think of it as a dinner party guest who’s willing to talk about more than the weather.

Luscious
The rich, opulent, and smooth taste of sweet wines and intensely fruity ones.

Lyre
A vine training method. More details may be found in my advice page on vine training techniques.