Vasodilator a. : 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.

Example:
Is caffeine a Vasodilator or vasoconstrictor? How does that make it ease the pain of headaches?

Taxonomy
Vasodilation, intracellular, blood vessels, relaxation, nitric oxide, extracellular, blood, peripheral vasodilators, vasodilator, TPR, intracellular calcium, dephosphorylation, MLCK, arterioles, ATP, free encyclopedia, mechanisms, intracellular calcium concentration.

Defination from the web:
vasodilator, causing lightheadedness and a euphoric feeling. ... Baroreflex · Kinin-kallikrein system · Renin-angiotensin system · Vasoconstrictors/Vasodilators · Autoregulation (Myogenic mechanism, Tubuloglomerular feedback) ...