资料来源 : Webster's Revised Unabridged Dictionary (1913)

Mail \Mail\, n. [OE. male bag, OF. male, F. malle bag, trunk,
   mail, OHG. malaha, malha, wallet; akin to D. maal, male; cf.
   Gael. & Ir. mala, Gr. ? hide, skin.]
   1. A bag; a wallet. [Obs.] --Chaucer.

   2. The bag or bags with the letters, papers, papers, or other
      matter contained therein, conveyed under public authority
      from one post office to another; the whole system of
      appliances used by government in the conveyance and
      delivery of mail matter.

            There is a mail come in to-day, with letters dated
            Hague.                                --Tatler.

   3. That which comes in the mail; letters, etc., received
      through the post office.

   4. A trunk, box, or bag, in which clothing, etc., may be
      carried. [Obs.] --Sir W. Scott.

   {Mail bag}, a bag in which mailed matter is conveyed under
      public authority.

   {Mail boat}, a boat that carries the mail.

   {Mail catcher}, an iron rod, or other contrivance, attached
      to a railroad car for catching a mail bag while the train
      is in motion.

   {Mail guard}, an officer whose duty it is to guard the public
      mails. [Eng.]

   {Mail train}, a railroad train carrying the mail.

资料来源 : WordNet®

mail train
     n : a train that carries mail