vasodilator

from WordNet (r) 3.0 (2006)

vasodilator
    n 1: a drug that causes dilation of blood vessels [syn:
         {vasodilator}, {vasodilative}]

from The Collaborative International Dictionary of English v.0.48

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.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Vasodilator \Vas`o*di*lat"or\, n. [L. vas a vessel + dilator.]
   (Medicine & Physiology)
   A substance which causes dilation of blood vessels.
   [PJC]