[1] : The Collaborative International Dictionary of English v.0.48

vasodilator \vas`odilat"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
see also:
vaso-inhibitory vasohypotonic 

[2] : The Collaborative International Dictionary of English v.0.48

vasodilator \vas`odilat"or\, n. l. vas a vessel + dilator.
   medicine  physiology
   a substance which causes dilation of blood vessels.
   pjc

[3] : WordNet (r) 2.0

vasodilator
     n : a drug that causes dilation of blood vessels syn: vasodilative
see also:
vasodilative 

Vasodilator >> V Words
Vasodilator, definition of term: Vasodilator
vasodilator_pag1.html