The Collaborative International Dictionary of English v.0.48:

Tintinnabulum \Tin`tin*nab"u*lum\, n.; pl. Tintinnabula. [L.,
   a bell. See Tintinnabular.]
   A bell; also, a set or combination of bells or metal plates
   used as a musical instrument or as a toy.
   [Webster 1913 Suppl.]