Medical Definition of hormone
1a: a product of living cells that circulates in body fluids (as blood) or sap and produces a specific often stimulatory effect on the activity of cells usually a distance from its point of synthesis <Some people develop insulin resistance, a condition in which response to the hormone is muted and the body must produce excess insulin to maintain healthy blood-glucose concentrations.—Ben Harder, Science News, 18 May 2002>b: a synthetic substance that acts like a hormone
2: sex hormone <I discovered I had the classic signs of perimenopause, the prelude to “the change” when hormones yo-yo before menstrual periods cease altogether …—Beth Witrogen McLeod, Cooking Light, April 2000>
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