Source : Webster's Revised Unabridged Dictionary (1913)

Bough \Bough\, n. [OE. bogh, AS. b[=o]g, b[=o]h, bough,
   shoulder; akin to Icel. b[=o]gr shoulder, bow of a ship, Sw.
   bog, Dan. bov, OHG. buog, G. bug, and to Gr.? ( for ? )
   forearm, Skr. b[=a]hu (for bh[=a]ghu) arm. [root]88, 251. Cf.
   {Bow} of a ship.]
   1. An arm or branch of a tree, esp. a large arm or main
      branch.

   2. A gallows. [Archaic] --Spenser.

Source : WordNet®

bough
     n : any of the larger branches of a tree