A glossary of Belgian beer.

An abbey-style beer brewed by a commercial brewery, often under license to a monastery or evoking monastic tradition, but not a true Trappist beer.

Alcohol by volume, the percentage of alcohol in the beer. Belgian ales range widely, from sub-4 percent table beers to quadrupels above 11 percent.

The ATP label, a hexagonal logo certifying that a beer is brewed inside a Trappist abbey under strict conditions. Only a handful of breweries qualify.

The pattern of foam that clings to the inside of the glass as you drink, a sign of good head retention and a clean glass.

A pale, potent, effervescent ale of around 8 to 9 percent, fruity and dangerously drinkable. Duvel set the template.

The art of marrying lambics or batches of different ages to build a balanced beer, the heart of gueuze making and the craft of the geuzesteker (blender).

A second fermentation that happens inside the sealed bottle, with added yeast and sugar producing natural carbonation and allowing the beer to mature and age.

A wild yeast (often shortened to Brett) that gives lambic, Orval and many sours their earthy, funky, hay-like and tart character, developing over months in the bottle.

Belgian rock or syrup sugar added to the boil to lift alcohol without adding body, and, in dark forms, to deepen color and add notes of caramel and dark fruit.

Aging strong, bottle-conditioned Belgian beers over months or years, softening their edges and developing deeper, sherry-like and dried-fruit notes.

A wide, heavy, stemmed goblet used for Trappist and abbey ales, opening up aroma and supporting a thick head. Many abbeys etch the glass bottom to spark carbonation.

A wide, shallow open vessel (koelschip in Flemish) where hot wort is left to cool overnight, exposing it to the wild airborne yeasts that start spontaneous fermentation.

A clean, crisp end with little residual sweetness, characteristic of well-attenuated Belgian ales like saison and tripel.

A dark, malty abbey ale of about 6 to 8 percent, rich with notes of dried fruit, caramel and spice.

Flemish for single, a modest table beer brewed for the monks' own daily use, lighter than the dubbel and tripel sold to the public. Also called a patersbier.

Fruity aroma compounds produced by warm ale fermentation, giving Belgian beers notes of banana, pear, apple and stone fruit.

A broad family of rustic, often dry rural ales, including saison, brewed historically on farms with whatever was at hand.

A traditional low-strength lambic sweetened with candi sugar, historically the everyday table beer of Brussels.

A tart, fruity, wine-like ale from West Flanders, aged for up to two years in large oak foeders. Rodenbach is the benchmark.

A tall, narrow glass that shows off the sparkle and fine bead of gueuze and other effervescent lambics.

A large upright oak vat, sometimes holding tens of thousands of liters, used to age and sour beers like Flanders red over months or years.

A lambic refermented with fruit, such as cherries (kriek) or raspberries (framboise), the fruit feeding a second fermentation.

The earthy, barnyard, leathery aroma imparted by Brettanomyces and wild fermentation, prized in lambic and aged sours.

A blendery that buys lambic from breweries and ages and blends it into gueuze, rather than brewing its own wort. 3 Fonteinen and Tilquin began this way.

A sparkling, dry, tart beer made by blending young and old lambics, then refermenting in the bottle. Often called the Champagne of Belgium.

A lambic or sour ale macerated with whole cherries (kriek is Flemish for cherry), yielding a tart, fruity, often dry beer.

A wheat beer from the Senne valley around Brussels, fermented spontaneously by wild yeast and bacteria rather than pitched yeast. Aged in oak, it is the base for gueuze, kriek and faro.

Fermentation using a blend of yeast and souring bacteria such as Lactobacillus and Pediococcus, central to Flanders reds and oud bruins.

Traditional European aroma hops prized for subtlety. In lambic, hops are deliberately aged until stale, used for preservation rather than bitterness or aroma.

An East Flanders brown ale, sweet-and-sour and lightly tart, blended from young and aged batches. Liefmans is the classic example.

The rural region southwest of Brussels, part of the Senne valley, whose terroir of wild airborne yeasts makes traditional lambic possible.

Spicy, clove-like aroma compounds from Belgian yeast, a signature of styles like witbier, saison and tripel.

A very strong, dark abbey ale of roughly 10 percent or more, layered with dark fruit, malt and warming alcohol. Also called a Belgian Dark Strong Ale.

A renewed fermentation triggered after the main one, whether in the bottle, keg or with added fruit, deepening flavor and carbonation.

A dry, spicy, highly carbonated farmhouse ale from Wallonia, originally brewed in winter to refresh seasonal farm workers (saisonniers) through summer.

The river valley around Brussels, the only place where the specific wild microflora needed for authentic lambic occur naturally.

Fermentation by wild yeast and bacteria carried on the air, rather than a pitched yeast strain. The defining method of lambic, possible only in and around the Senne valley.

Warm fermentation with ale yeast that rises to the surface, used for nearly all classic Belgian ales and producing fruity, spicy character.

Beer brewed within the walls of a Trappist monastery, by or under the supervision of the monks, with profits supporting the community. A designation of origin, not a style.

A strong, golden, deceptively smooth ale of around 8 to 9.5 percent, defined by Westmalle in the 1930s. Spicy and bright, with a dry finish.

A stemmed glass that curves out then in, capturing aroma and holding a dense head. Favored for strong golden ales and many Belgian ales.

A complex traditional mashing method used for lambic, leaving unconverted starches that feed the wild microbes through a long fermentation.

A pale, cloudy wheat beer spiced with coriander and orange peel. The style nearly died out before Pierre Celis revived it in Hoegaarden in 1966.