Source : Webster's Revised Unabridged Dictionary (1913)

Bassoon \Bas*soon"\, n. [F. basson, fr. basse bass; or perh. fr.
   bas son low sound. See {Bass} a part in music. ] (Mus.)
   A wind instrument of the double reed kind, furnished with
   holes, which are stopped by the fingers, and by keys, as in
   flutes. It forms the natural bass to the oboe, clarinet, etc.

   Note: Its compass comprehends three octaves. For convenience
         of carriage it is divided into two parts; whence it is
         also called a fagot.

Source : WordNet®

bassoon
     n : a double-reed instrument; the tenor of the oboe family