Eicosatetraenoic acid designates any straight chain 20:4 fatty acid. In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...

See essential fatty acid#Nomenclature for nomenclature.

Two isomers, both of them essential fatty acids, are of particular interest Essential fatty acids, or EFAs, are fatty acids that are required in the human diet. ... Essential fatty acids, or EFAs, are fatty acids that are required in the human diet. ...

• all-cis 5,8,11,14-eicosatetraenoic acid is an ω-6 fatty acid with the trivial name arachidonic acid. It is formed by a desaturation of dihomo-gamma-linolenic acid 20:4 ω-6.
• all-cis 8,11,14,17-eicosatetraenoic acid is an ω-3 fatty acid. It is an intermediary between stearidonic acid (18:4 ω-3) and eicosapentaenoic acid (EPA, 20:5 ω-3)

Some Chemistry sources define 'arachadonic acid' to designate any of the eicosatetraenoic acids. However, almost all writings in Biology, Medicine and Nutrition limit the use the term 'arachidonic acid' to all-cis 5,8,11,14-eicosatetraenoic acid (ω-6). Omega-6 fatty acids are fatty acids where the term omega-6 signifies that the first double bond in the carbon backbone of the fatty acid, counting from the end opposite the acid group, occurs in the sixth carbon-carbon bond. ... Arachidonic acid is a polyunsaturated fatty acid with twenty carbons and four cis double bonds, the first at the omega-6 position (20:4n-6). ... Dihomo-gamma-linolenic acid (DGLA) is 20-carbon ω-3 fatty acid. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Eicosapentaenoic acid (more commonly known as EPA; C20H30O2, all-cis-fatty acid 20:5 omega-3) is a polyunsaturated fatty acid that acts as a precursor for prostaglandin-3, which inhibits platelet aggregation) and thromboxane-3 groups. ...