Source : Webster's Revised Unabridged Dictionary (1913)

Lager beer \La"ger beer`\ [G. lager bed, storehouse + bier beer.
   See {Lair}, and {Beer}.]
   Originally a German beer, but now also made in immense
   quantities in the United States; -- so called from its being
   laid up or stored for some months before use.

Source : WordNet®

lager beer
     n : a general term for beer made with bottom fermenting yeast
         (usually by decoction mashing); originally it was brewed
         in March or April and matured until September [syn: {lager}]