Vasa

from The Collaborative International Dictionary of English v.0.48

Vas \Vas\, n.; pl. {Vasa}. [L., a vessel. See {Vase}.] (Anat.)
   A vessel; a duct.
   [1913 Webster]

   {Vas deferens}; pl. {Vasa deferentia}. [L. vas vessel +
      deferens carrying down.] (Anat.) The excretory duct of a
      testicle; a spermatic duct.
      [1913 Webster]