What is the meaning of Fatty_acid?

Any of a class of aliphatic carboxylic acids, of general formula CnH2n+1COOH, that occur combined with glycerol as animal or vegetable oils and fats. Only those with an even number of carbon atoms are normally found in natural fats.

The above general formula applies to the saturated fatty acids. Remove 2 hydrogen atoms for an unsaturated fatty acid, and 2 hydrogen atoms for every double bond in a polyunsaturated fatty acid.

Source: wiktionary.org