From The Collaborative International Dictionary of English v.0.48 [gcide]:
Beer \Beer\, n. [OE. beor, ber, AS. be['o]r; akin to Fries.
biar, Icel. bj?rr, OHG. bior, D. & G. bier, and possibly E.
brew. [root]93, See Brew.]
1. A fermented liquor made from any malted grain, but
commonly from barley malt, with hops or some other
substance to impart a bitter flavor.
[1913 Webster]
Note: Beer has different names, as small beer, ale,
porter, brown stout, lager beer, according to its
strength, or other qualities. See Ale.
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2. A fermented extract of the roots and other parts of
various plants, as spruce, ginger, sassafras, etc.
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Small beer, weak beer; (fig.) insignificant matters. "To
suckle fools, and chronicle small beer." --Shak.
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From WordNet (r) 3.0 (2006) [wn]:
beer
n 1: a general name for alcoholic beverages made by fermenting a
cereal (or mixture of cereals) flavored with hops