noun, a hormone that is secreted by the adrenal medulla in response to stress and increases heart rate, pulse rate, and blood pressure, and raises the blood levels of glucose and lipids. It is extracted from animals or synthesized for such medical uses as the treatment of asthma. Chemical name: aminohydroxyphenylpropionic acid; formula: C₉H₁₃NO₃. US name: epinephrine

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©HarperCollins 2008. Collins English Dictionary definition of adrenaline