Source : Webster's Revised Unabridged Dictionary (1913)

Itaconic \It`a*con"ic\, a. [From aconitic, by transposition of
   the letters.] (Chem.)
   Pertaining to, or designating, an acid, {C5H6O4}, which is
   obtained as a white crystalline substance by decomposing
   aconitic and other organic acids.