Source : Webster's Revised Unabridged Dictionary (1913)

Mail \Mail\, n. [OE. maile, maille, F. maille a ring of mail,
   mesh, network, a coat of mail, fr. L. macula spot, a mesh of
   a net. Cf. {Macle}, {Macula}, {Mascle}.]
   1. A flexible fabric made of metal rings interlinked. It was
      used especially for defensive armor. --Chaucer.

   {Chain mail}, {Coat of mail}. See under {Chain}, and {Coat}.

   2. Hence generally, armor, or any defensive covering.

   3. (Naut.) A contrivance of interlinked rings, for rubbing
      off the loose hemp on lines and white cordage.

   4. (Zo["o]l.) Any hard protective covering of an animal, as
      the scales and plates of reptiles, shell of a lobster,
      etc.

            We . . . strip the lobster of his scarlet mail.
                                                  --Gay.

Coat \Coat\ (k[=o]t; 110), n. [OF. cote, F. cotte, petticoat,
   cotte d'armes coat of arms, cotte de mailles coat of mail,
   LL. cota, cotta, tunic, prob. of German origin; cf. OHG.
   chozzo coarse mantle, G. klotze, D. kot, hut, E. cot. Cf.
   {Cot} a hut.]
   1. An outer garment fitting the upper part of the body;
      especially, such a garment worn by men.

            Let each His adamantine coat gird well. --Milton.

   2. A petticoat. [Obs.] ``A child in coats.'' --Locke.

   3. The habit or vesture of an order of men, indicating the
      order or office; cloth.

            Men of his coat should be minding their prayers.
                                                  --Swift.

            She was sought by spirits of richest coat. --Shak.

   4. An external covering like a garment, as fur, skin, wool,
      husk, or bark; as, the horses coats were sleek.

            Fruit of all kinds, in coat Rough or smooth rined,
            or bearded husk, or shell.            --Milton.

   5. A layer of any substance covering another; a cover; a
      tegument; as, the coats of the eye; the coats of an onion;
      a coat of tar or varnish.

   6. Same as Coat of arms. See below.

            Hark, countrymen! either renew the fight, Or tear
            the lions out of England's coat.      --Shak.

   7. A coat card. See below. [Obs.]

            Here's a trick of discarded cards of us! We were
            ranked with coats as long as old master lived.
                                                  --Massinger.

   {Coat armor}. See under {Armor}.

   {Coat of arms} (Her.), a translation of the French cotte
      d'armes, a garment of light material worn over the armor
      in the 15th and 16th centuries. This was often charged
      with the heraldic bearings of the wearer. Hence, an
      heraldic achievement; the bearings of any person, taken
      together.

   {Coat card}, a card bearing a coated figure; the king, queen,
      or knave of playing cards. ```I am a coat card indeed.'
      `Then thou must needs be a knave, for thou art neither
      king nor queen.''' --Rowley.

   {Coat link}, a pair of buttons or studs joined by a link, to
      hold together the lappels of a double-breasted coat; or a
      button with a loop for a single-breasted coat.

   {Coat of mail}, a defensive garment of chain mail. See {Chain
      mail}, under {Chain}.

   {Mast coat} (Naut.), a piece of canvas nailed around a mast,
      where it passes through the deck, to prevent water from
      getting below.

   {Sail coat} (Naut.), a canvas cover laced over furled sails,
      and the like, to keep them dry and clean.

Source : WordNet®

coat of mail
     n : armor that protects the wearer's whole body [syn: {body
         armor}, {body armour}, {suit of armor}, {suit of armour},
          {cataphract}]