Beer has many ways to capture a man’s attention as you know, but one of the things that specially endears the hobby to me is the obscure vocabulary that goes along with brewing, or zymurgy as it is also known.
For starters, there is the word ‘beer’ itself. Indeed, the words ‘beer’, ‘ale’ ‘stout’ and ‘porter’ are all a nice case study in the historical dimension of meaning. At present, the average Joe probably takes ‘beer’ to be the general term for an alcoholic drink made from fermented malted barley, ‘ale’ to be an old-fashioned but otherwise synonymous word for beer, and ‘stout’ and ‘porter’ to be equivalent words for thickish dark beer. But there’s much more to it. According to C.J.J Berry , Old English did have a word ‘beor’ but it’s not clear whether this was a malt based drink at all or a form of mead. In any case, people stopped using it from AD950 and used ‘ale’ instead. In the fifteenth century, beer made a reappearance, now spelled ‘bere’ or ‘biere’, for an alcoholic malt based drink that was, crucially, made with hops, lately introduced from the Continent. ‘Ale’ continued to be used for unhopped beer. Beer was hopped ale. Ale was unhopped beer. Eventually, of course, the use of hops in brewing became ubiquitous and this distinction was lost. Prior to the arrival of hops, brewers used a variety of herbs such as nettles, bog myrtle, spruce and heather to flavour their ale. These additions were known as ‘grout’ or ‘gruit’.
The history of the words ‘stout’ and ‘porter’ is similarly storied and round-about. In the middle of the 18th century, the porters of London developed a taste for a mixture of ‘stale,’ i.e. aged, and fresh beers, which came to be called ‘porter’. Some enterprising brewer started brewing a beer that was ‘entire’, i.e. a single beer that tasted like the porter blend, which caught on because it cut out the need for aging and conditioning the beer, which is expensive because you have stock sitting around not being sold. Porter was dark because it was made with a blend of darkly kilned malts, but as technology developed it became possible to roast malts until they were virtually reduced to ashes. This was useful because it meant one could get the same colour with less of the expensive highly kilned malt. In Ireland, to avoid some of the high tax on malt, brewers used roasted unmalted barley to produce porter. Stout originally meant strong porter, but the classic stout these days, Guinness, is a modest 4.3%. Today you could say a ‘stout’ is simply a very dark porter made with some proportion of roasted unmalted barley.
Lager is something different again. The ordinary person’s conception of lager as a light coloured, clean, dry-tasting, highly carbonated beer doesn’t touch the true point of departure from other beers. British and Irish beers, ales and stouts are all made with strains of top-fermenting yeast of the species saccharomyces cerevisiae. A top-fermenting yeast sits on top of the wort eating its sugars and turning them into carbon dioxide and alcohol. Additionally, top-fermenters all work at a temperature range of between 18-24 degrees Celcius. Lagers on the other hand use a different, bottom-fermenting, strain of yeast, saccharomyces carlsbergensis (a.k.a. sacchahromyces pastorianus), which is active at much lower temperatures (5-12’C). They are also ‘lagered,’ that is, stored at near freezing temperatures. A beer is a lager as long as it uses that yeast and is lagered irrespective of how light and fizzy it is. (I’ve never brewed a lager because the lagering process isn’t really reproduceable at a domestic level).
So perhaps we should say that ‘beer’ is a general term encompassing two principal varieties ‘ale’ and ‘lager’, and that on this island we’re especially fond of a sub-variety of ale known as stout porter or just stout.
Here are some other words in the brewer’s vocabulary:
grout (or gruit): noun. from Dutch. plants used for flavouring beer before the use of hops.
gyle: noun. from Dutch. a batch of beer, as in ‘I’ve done two gyles this month’, i.e I’ve brewed twice this month.
trub: noun. the dregs at the bottom of the copper and the fermentation vessel composed of dead and dormant yeast, precipated proteins and other nasties. Note this usage is not in the OED as of Monday 20th June 2011. The OED gives two senses for ‘trub’; a truffle and ‘A little squat woman’ (Phillips 1706); also, ‘a slut, sloven; a wanton; an opprobrious term’( Eng. Dial. Dict.).
mash: verb. to steep malted barley in water at between 65 and 68 degrees Celcius to convert starches in the malt to fermentable sugars (maltose).
mashtun: vessel in which mashing occurs.
wort: noun. the product of mashing. beer before it is fermented
copper: vessel used to boil wort.
liquor: water for brewing
Speise: noun. from German, wort sometimes added to beer at bottling time to provide a source of sugars for carbonation
Krausen: noun. from German, the froth of fermentation; also the addition of freshly fermenting wort to beer at bottling time to carbonate the beer.
 “Home Brewed Beers and Stouts” Andover, Hampshire: Amateur Winemaker, 1963. p14