C2H2CO2H2

Fumaric Fu*mar"ic, a. (Chem.) Pertaining to, or derived from, fumitory ({Fumaria officinalis}). [1913 Webster]

{Fumaric acid} (Chem.), a widely occurring organic acid, extracted from fumitory as a white crystallline substance, {C2H2(CO2H)2}, and produced artificially in many ways, as by the distillation of malic acid; boletic acid. It is found also in the lichen, Iceland moss, and hence was also called {lichenic acid}. [1913 Webster]