Source : Webster's Revised Unabridged Dictionary (1913)

Saxhorn \Sax"horn`\, n. (Mus.)
   A name given to a numerous family of brass wind instruments
   with valves, invented by Antoine Joseph Adolphe Sax (known as
   Adolphe Sax), of Belgium and Paris, and much used in military
   bands and in orchestras.

Source : WordNet®

saxhorn
     n : any of a family of brass wind instruments that resemble a
         bugle with valves