The Collaborative International Dictionary of English v.0.48:

Beech \Beech\, n.; pl. Beeches. [OE. beche, AS. b?ce; akin to
   D. beuk, OHG. buocha, G. buche, Icel. beyki, Dan. b["o]g, Sw.
   bok, Russ. buk, L. fagus, Gr. ? oak, ? to eat, Skr. bhaksh;
   the tree being named originally from the esculent fruit. See
   Book, and cf. 7th Buck, Buckwheat.] (Bot.)
   A tree of the genus Fagus.
   [1913 Webster]

   Note: It grows to a large size, having a smooth bark and
         thick foliage, and bears an edible triangular nut, of
         which swine are fond. The Fagus sylvatica is the
         European species, and the Fagus ferruginea that of
         America.
         [1913 Webster]

   Beech drops (Bot.), a parasitic plant which grows on the
      roots of beeches (Epiphegus Americana).

   Beech marten (Zool.), the stone marten of Europe (Mustela
      foina).

   Beech mast, the nuts of the beech, esp. as they lie under
      the trees, in autumn.

   Beech oil, oil expressed from the mast or nuts of the beech
      tree.

   Cooper beech, a variety of the European beech with
      copper-colored, shining leaves.
      [1913 Webster]

WordNet (r) 3.0 (2006):

beech
    n 1: any of several large deciduous trees with rounded spreading
         crowns and smooth grey bark and small sweet edible
         triangular nuts enclosed in burs; north temperate regions
         [syn: beech, beech tree]
    2: wood of any of various beech trees; used for flooring and
       containers and plywood and tool handles [syn: beech,
       beechwood]