Alpha Acid - the acids in hops that affect their bitterness. Shown as a percentage.
Beta Acid - the acids in hops that help inhibit bacterial growth and spoilage. Not usually a big factor in most home brews.
Hop Utilization - how efficiently your wort is dissolving the alpha acids from your hops into solution.
AAU/HBU – the potential bitterness from hops derived from the Alpha Acids in the hops. One ounce of hops with 1 percent alpha acids contain 1AAU. One ounce of hops with 2 percent alpha acids contain 2AAUs. Similarly, HBUs can be used the same way. Two ounces of hops with 10 percent alpha acids would equal 20HBUs. Because the Alpha Acids change with every harvest, most beer recipes will specify how many HBUs or AAUs of hops are needed.
IBU - International Bittering Units is a measurement gauging the bitterness of your final beer. If you know your boil time and potential hop utilization you can predict your IBUs form the total AAUs/HBUs in your recipe. For a quick understanding of the IBU scale, Blondes can be 10-20 IBUs, Pale Ales can be 20-40 IBUs, IPAs can be 40-80 IBUs, and Imperial IPAs can be 60-120+ IBUs.
Wet Hops - fresh hops right off the vine. You need 6 times the amount of we hops to equal that of dried leaf or pellet hops.
Dry Hopping - adding hops to your secondary fermenter to boost the hop aroma of your beer.
ABV/ABW - alcohol by volume and alcohol by weight. The alcohol in most beer in most parts of the world is measured by volume. ABV is the easiest and most popular way to measure alcohol in home brewing also. Utah measures alcohol by weight which is a bit confusing for many since it appears lower than when measured by volume. 3.2%abw beer in Utah is the same as 4.0%abv beer everywhere else.
Grain Bill - the type and amount of grain used in your beer. The grain part of a beer recipe.
Lovebond - this is a measurement of the color of grain after it is kilned or roasted.
SRM - this is a measurement of color in your final beer.
Trub - the gross and often smelly stuff at the bottom of your beer after fermentation. This is a mixture of yeast, hops, and grain particulates along with heavy proteins that have been pulled or fallen out of suspension over time.
Cold Crashing - cooling down your fermented beer for a short period of time, usually less than 24 hrs, before bottling with the intention of forcing more particulates to fall out of suspension making for a clearer final product.
Fining - making your beer, mead, cider, or wine clear.
Lagering - cold aging beer.
Ale - warm fermented beer.
Lager - cold fermented beer.
Sour Beer - this refers to beer that has been intentionally infected with specific strains of bacteria or wild yeast to impart a sour or tart flavor.
Pellicle - a lumpy, or slimy film that looks much like mold that forms when wild yeast or bacteria like brettanomyces is introduced to your beer. This can be intentional or by accident, but either way you will want to isolate any equipment you use with this contaminated beer and use it only for sour beers.
Diacetyl Rest - the act of warming your cold fermented beer just before lagering to reduce the amount of diacetyl (butter flavor) in the final beer. Raising the fermentation temp at the end of primary fermentation to 60°F for a couple days before cold aging your beer gives yeast a chance to consume the diacetyl.
Primary Fermentation - the aggressive yeast activity that does much of the work converting sugar to alcohol.
Secondary Fermentation - transferring your beer to a different vessel after primary fermentation. This is where your beer will age and clear in the absence of most of the trub that is produced during primary fermentation. This can also be the time to dry hop or start another kind of fermentation by adding either fruit or other fermentables or by adding bacteria.
Tertiary fermentation - a fancy word for Third fermentation, this is where you age and clear your beer if you started up fermentation again during your secondary fermentation.