Source : Webster's Revised Unabridged Dictionary (1913)

Vas \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.

Source : WordNet®

vas deferens
     n : a duct that carries spermatozoa from the epididymis to the
         ejaculatory duct [syn: {ductus deferens}]