The Collaborative International Dictionary of English v.0.48:

Theobromine \The`o*bro"mine\, n. (Chem.)
   An alkaloidal ureide, C7H8N4O2, homologous with and
   resembling caffeine, produced artificially, and also
   extracted from cacao and chocolate (from Theobroma Cacao)
   as a bitter white crystalline substance; -- called also
   dimethyl xanthine.
   [1913 Webster]