\Vas\, n.; pl. {Vasa}. [L., a vessel. See {Vase}.] (Anat.)
A vessel; a duct.

{Vas deferens}; pl. {Vasa deferentia}. [L. vas vessel +
   deferens carrying down.] (Anat.) The excretory duct of a
   testicle; a spermatic duct.