The Collaborative International Dictionary of English v.0.48:

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.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tom-tom \Tom"-tom`\ (t[o^]m"t[o^]m`), n.
   See Tam-tam.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tom-tom
    n 1: any of various drums with small heads [syn: tenor drum,
         tom-tom]