Source : Webster's Revised Unabridged Dictionary (1913)

Diamine \Di*am"ine\ (?; 104), n. [Pref. di- + amine.] (Chem.)
   A compound containing two amido groups united with one or
   more basic or positive radicals, -- as contrasted with a
   diamide.

   Note: In chemical nomenclature, if any amine or diamine is
         named by prefixing the nitrogen group, the name of the
         latter takes the form of amido, diamido, etc., thus
         ethylene diamine, {C2H4.(NH2)2}, is also called
         diamido-ethylene.

Source : WordNet®

diamine
     n : any organic compound containing two amino groups