| ̷ ̷ ̷ ̷ at iso- +...- noun
: a crystalline acid HOOCCH(OH)CH(COOH)CH 2 COOH isomeric with citric acid that is found especially in the leaves of various air plants of the genus Kalanchoe and in blackberry juice and is recognized as an intermediate stage in the metabolism of fats and carbohydrates; 2-hydroxy-1,2,3-propane-tricarboxylic acid