Organic compounds containing the group –CO.OH (the carboxyl group; i.e. a carbonyl group attached to a hydroxyl group). In systematic chemical nomenclature carboxylic-acid names end in the suffix -oic, e.g. ethanoic acid, CH3COOH. They are generally weak acids. Many long-chain carboxylic acids occur naturally as esters in fats and oils and are therefore also known as fatty acids. See also glycerides.
https://www.acdlabs.com/iupac/nomenclature/93/r93_480.htm Information about IUPAC nomenclature