fumaric acid

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An organic acid, C₄H₄O₄, found in various plants and produced synthetically and used mainly in resins, paints, varnishes, and inks.

Wiktionary

1. n. organic chemistry 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

GNU Webster's 1913

1. adj. (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.

WordNet 3.0

1. n. a colorless crystalline acid with a fruity taste; used in making polyester resins