Source : Webster's Revised Unabridged Dictionary (1913)

Flat \Flat\, a. [Compar. {Flatter}; superl. {Flattest}.] [Akin
   to Icel. flatr, Sw. flat, Dan. flad, OHG. flaz, and AS. flet
   floor, G. fl["o]tz stratum, layer.]
   1. Having an even and horizontal surface, or nearly so,
      without prominences or depressions; level without
      inclination; plane.

            Though sun and moon Were in the flat sea sunk.
                                                  --Milton.

   2. Lying at full length, or spread out, upon the ground;
      level with the ground or earth; prostrate; as, to lie flat
      on the ground; hence, fallen; laid low; ruined; destroyed.

            What ruins kingdoms, and lays cities flat! --Milton.

            I feel . . . my hopes all flat.       --Milton.

   3. (Fine Arts) Wanting relief; destitute of variety; without
      points of prominence and striking interest.

            A large part of the work is, to me, very flat.
                                                  --Coleridge.

   4. Tasteless; stale; vapid; insipid; dead; as, fruit or drink
      flat to the taste.

   5. Unanimated; dull; uninteresting; without point or spirit;
      monotonous; as, a flat speech or composition.

            How weary, stale, flat, and unprofitable Seem to me
            all the uses of this world.           --Shak.

   6. Lacking liveliness of commercial exchange and dealings;
      depressed; dull; as, the market is flat.

   7. Clear; unmistakable; peremptory; absolute; positive;
      downright.

            Flat burglary as ever was committed.  --Shak.

            A great tobacco taker too, -- that's flat.
                                                  --Marston.

   8. (Mus.)
      (a) Below the true pitch; hence, as applied to intervals,
          minor, or lower by a half step; as, a flat seventh; A
          flat.
      (b) Not sharp or shrill; not acute; as, a flat sound.

   9. (Phonetics) Sonant; vocal; -- applied to any one of the
      sonant or vocal consonants, as distinguished from a
      nonsonant (or sharp) consonant.

   {Flat arch}. (Arch.) See under {Arch}, n., 2. (b).

   {Flat cap}, cap paper, not folded. See under {Paper}.

   {Flat chasing}, in fine art metal working, a mode of
      ornamenting silverware, etc., producing figures by dots
      and lines made with a punching tool. --Knight.

   {Flat chisel}, a sculptor's chisel for smoothing.

   {Flat file}, a file wider than its thickness, and of
      rectangular section. See {File}.

   {Flat nail}, a small, sharp-pointed, wrought nail, with a
      flat, thin head, larger than a tack. --Knight.

   {Flat paper}, paper which has not been folded.

   {Flat rail}, a railroad rail consisting of a simple flat bar
      spiked to a longitudinal sleeper.

   {Flat rods} (Mining), horizontal or inclined connecting rods,
      for transmitting motion to pump rods at a distance.
      --Raymond.

   {Flat rope}, a rope made by plaiting instead of twisting;
      gasket; sennit.

   Note: Some flat hoisting ropes, as for mining shafts, are
         made by sewing together a number of ropes, making a
         wide, flat band. --Knight.

   {Flat space}. (Geom.) See {Euclidian space}.

   {Flat stitch}, the process of wood engraving. [Obs.] -- {Flat
   tint} (Painting), a coat of water color of one uniform shade.
      

   {To fall flat} (Fig.), to produce no effect; to fail in the
      intended effect; as, his speech fell flat.

            Of all who fell by saber or by shot, Not one fell
            half so flat as Walter Scott.         --Lord
                                                  Erskine.