Vasodilator \Vas`o*di*lat"or\, a.[L. vas a vessel + dilator.] (Physiol.) Causing dilation or relaxation of the blood vessels; as, the vasodilator nerves, stimulation of which causes dilation of the blood vessels to which they go. These nerves are also called {vaso-inhibitory}, and {vasohypotonic} nerves, since their stimulation causes relaxation and rest.