oxaloacetic acid

Noun

 * 1) One of the constituents of the citric acid cycle, formed by the oxidation of malic acid and via the transamination of aspartic acid; an intermediate in the synthesis of amino acids and the metabolism of carbohydrates
 * 2)  a colourless crystalline organic carboxylic acid, butan-2-one-1,4-dicarboxylic acid, COOH.CH$2$.CO.COOH