I. noun — [ mass noun] 1.
[Biochemistry] a polyunsaturated fatty acid present in animal fats. It is important in metabolism, especially in the synthesis of prostaglandins and leukotrienes, and is an essential constituent of the diet.●Alternative name: eicosa-5,8,11,14-enoic acid; chem. formula: C19H31COOH.
– origin early 20th cent.: arachidonic formed irregularly from arachidic (a saturated fatty acid) from Latin arachis, see arachis oil, + -one + -ic.