oleic acidPronunciation: /əʊˈliːɪk/Definition of oleic acid noun [mass noun] Chemistry an unsaturated fatty acid present in many fats and soaps. Chemical formula: CH3(CH2)7CHCH(CH2)7COOH Origin: early 19th century: oleic from Latin oleum 'oil'oleic acid in other Oxford dictionaries Definition of oleic acid in the US English dictionary