any of various compounds, as norepinephrine and dopamine, that are secretions, or byproducts of secretions, of the medulla of the adrenal gland and that affect the sympathetic nervous system
See catecholamine in American Heritage Dictionary 4
(kătˌĭ-kōˈlə-mēnˌ, -kôˌ-)
noun
Any of a group of amines derived from catechol that have important physiological effects as neurotransmitters and hormones and include epinephrine, norepinephrine, and dopamine.