from
The Collaborative International Dictionary of English v.0.48
maleic acid \maleic acid\ n. (Chem.)
An unsaturated dicarboxylic acid ({HO.CO.CH=CH.CO.OH}) of cis
conformation, having various uses in the manufacture of
artificial resins, the dyeing and finishing of wool, silk,
and cotton, and also combined with certain drugs to make
salts more soluble than the basic forms. The corresponding
isomer having trans conformation, is identical in chemical
formula, is called {fumaric acid}. --MI11
[PJC]