Vasodilator /(?)/

Vas·o·di·lat·or

Vasodilator

a.
  1. 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. (Physiol.)

Vasodilator

n.
  1. A substance which causes dilation of blood vessels. (Medicine & Physiology)