You'll be able to “speak bourbon” like an expert when you know the language. These are the terms you will encounter on bourbon labels.
Aging: Bourbon must be aged in charred, never-before-used barrels traditionally made of white oak (Quercus alba) for at least two years. Most are aged between five and eight years.
Bourbon: Whiskey distilled from fermented grain. By law, at least 51 percent of the mash bill (grains used) must be corn. Other grains used are typically barley and rye in varying proportions. Wheat is sometimes used in place of rye; such whiskeys are called “wheated”bourbons. Maker's Mark and Old Fitzgerald are examples of wheated bourbons.
The name “bourbon” is said by some to come from Bourbon County, Kentucky, named to honor the French royal family that aided the American colonists during the War for Independence. But no one really knows for certain where the name came from.
Proof: Equal to twice the alcohol content by volume. Hence, an 86 proof bourbon is 43 percent alcohol. Proofs are adjusted by the addition of water after aging. A barrel proof bourbon has not been so adjusted. These are typically 110 proof and higher.
Single barrel: The bottling is all from one selected barrel.
Small batch: A limited production of bourbon using select, mixed barrels.
Sour mash: The soupy alcoholic liquid strained from the first distillation and added to the next batch of grain for distillation (rather like a sourdough starter). Also called “backset.” Dr. James Crowe, a Scot who came to Kentucky in the nineteenth century, developed the technique to help keep bourbon consistent from one distillation to the next.
Straight bourbon whiskey: The legal definition of American bourbon says that “straight bourbon” is made up of at least 51 percent corn; is distilled at no more than 80 percent alcohol; is matured at no higher than 62.5 percent alcohol; and is matured in new charred oak barrels for no less than two years. It is bottled at a minimum of 40 percent alcohol by volume.
Whiskey (spelled “whisky” in Europe): An alcoholic beverage made from distilled grain. Bourbon is one of many whiskeys, including Scotch, Canadian, Irish, rye, Tennessee, and Kentucky whiskey. The last differs from bourbon in being aged in used charred oak barrels.