The Collaborative International Dictionary of English v.0.48:

Diureide \Di*u"re*ide\, n. [Di- + ureide.] (Chem.)
   One of a series of complex nitrogenous substances regarded as
   containing two molecules of urea or their radicals, as uric
   acid or allantoin. Cf. Ureide.
   [1913 Webster]