any of a group of hormonelike fatty acids found throughout the body, esp. in semen, that affect blood pressure, metabolism, body temperature, and other important body processes
See prostaglandin in American Heritage Dictionary 4
(prŏsˌtə-glănˈdĭn)
noun
Any of a group of potent hormonelike substances that are produced in various mammalian tissues, are derived from arachidonic acid, and mediate a wide range of physiological functions, such as control of blood pressure, contraction of smooth muscle, and modulation of inflammation.