Source : Webster's Revised Unabridged Dictionary (1913)

Plat \Plat\, n. [Cf. {Plat} flat, which perh. caused this
   spelling, and {Plot} a piece of ground.]
   A small piece or plot of ground laid out with some design, or
   for a special use; usually, a portion of flat, even ground.

         This flowery plat, the sweet recess of Eve. --Milton.

         I keep smooth plat of fruitful ground.   --Tennyson.

Plat \Plat\, v. t.
   To lay out in plats or plots, as ground.

Plat \Plat\, a. [F. plat. See {Plate}, n.]
   Plain; flat; level. [Obs.] --Gower.

Plat \Plat\, n.
   1. The flat or broad side of a sword. [Obs. or Prov. Eng.]
      --Chaucer.

   2. A plot; a plan; a design; a diagram; a map; a chart. [Obs.
      or Prov. Eng.] ``To note all the islands, and to set them
      down in plat.'' --Hakluyt.

Plat \Plat\, adv.
   1. Plainly; flatly; downright. [Obs.]

            But, sir, ye lie, I tell you plat.    --Rom. of R.

   2. Flatly; smoothly; evenly. [Obs.] --Drant.

Plat \Plat\, v. t. [imp. & p. p. {Platted}; p. pr. & vb. n.
   {Platting}.] [See {Plait}.]
   To form by interlaying interweaving; to braid; to plait.
   ``They had platted a crown of thorns.'' --Matt. xxvii. 29.

Plat \Plat\, n.
   Work done by platting or braiding; a plait.

         Her hair, nor loose, nor tied in formal plat. --Shak.

Source : WordNet®

plat
     n : a map showing planned or actual features of an area (streets
         and building lots etc.)
     [also: {platting}, {platted}]

plat
     v : make a plat of; "Plat the town" [syn: {plot}]
     [also: {platting}, {platted}]