Source : Webster's Revised Unabridged Dictionary (1913)

Tam-tam \Tam"-tam`\, n. [Hind.; of imitative origin.] (Mus.)
   (a) A kind of drum used in the East Indies and other Oriental
       countries; -- called also {tom-tom}.
   (b) A gong. See {Gong}, n., 1.

Source : WordNet®

tam-tam
     n : a percussion instrument consisting of a metal plate that is
         struck with a soft-headed drumstick [syn: {gong}]