The Collaborative International Dictionary
Fumaric \Fu*mar"ic\, a. (Chem.) Pertaining to, or derived from, fumitory ( Fumaria officinalis).
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.
Wiktionary
n. (context organic compound English) an unsaturated organic dicarboxylic acid, HOOCCH=CHCOOH, the geometric isomer of maleic acid from which it may be prepared by heating; it is found in many plants, including fungi and mosses, and is essential in the chemistry of respiration; it has a number of industrial applications, and its esters, the fumarates are used in the treatment of psoriasis
WordNet
n. a colorless crystalline acid with a fruity taste; used in making polyester resins
Wikipedia
Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HOCCH=CHCOH. This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid. In fumaric acid the carboxylic acid groups are trans (E) and in maleic acid they are cis (Z). Fumaric acid has a fruit-like taste. The salts and esters are known as fumarates.
Usage examples of "fumaric acid".
It also contains a little sugar, fumaric acid, oxalic acid, about 3 per cent of cetrarin and 1 per cent of licheno-stearic acid.