Noun

1. An amine, C₅H₉N₃, formed by decarboxylation of histidine, that causes dilatation of capillaries, contraction of smooth muscle, and stimulation of gastric acid secretion; it is released during allergic reactions.
   • 2001, Leslie Iversen, Drugs: A Very Short Introduction (Oxford 2001, p. 46)

     The intake of food triggers a release of histamine, which activates the acid-secreting cells.