Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated omega-9 fatty acid, abbreviated with a lipid number of 18:1 cis-9. It has the formula CH₃(CH₂)₇CH=CH(CH₂)₇COOH. The term "oleic" means related to, or derived from, oil of olive, the oil that is predominantly composed of oleic acid.