ˈ ̷ ̷ ̷ ̷ ̷ ̷ ˌ ̷ ̷ ̷ ̷ noun
: any of a group of receptors that are postulated to exist on cell surfaces of some effector organs and tissues innervated by the sympathetic nervous system to explain the specificity of certain adrenergic agents in activating or blocking only some sympathetic activities (as vasoconstriction, relaxation of intestinal muscle, and contraction of most smooth muscle) — compare beta-receptor herein