n. 1. A level surface, without elevation, relief, or prominences; an extended plain; specifically, in the United States, a level tract along the along the banks of a river; as, the Mohawk Flats. [ 1913 Webster ]

Envy is as the sunbeams that beat hotter upon a bank, or steep rising ground, than upon a flat. Bacon. [ 1913 Webster ]

2. A level tract lying at little depth below the surface of water, or alternately covered and left bare by the tide; a shoal; a shallow; a strand. [ 1913 Webster ]

Half my power, this night
Passing these flats, are taken by the tide. Shak. [ 1913 Webster ]

3. Something broad and flat in form; as: (a) A flat-bottomed boat, without keel, and of small draught. (b) A straw hat, broad-brimmed and low-crowned. (c) (Railroad Mach.) A car without a roof, the body of which is a platform without sides; a platform car. (d) A platform on wheel, upon which emblematic designs, etc., are carried in processions. [ 1913 Webster ]

4. The flat part, or side, of anything; as, the broad side of a blade, as distinguished from its edge. [ 1913 Webster ]

5. (Arch.) A floor, loft, or story in a building; especially, a floor of a house, which forms a complete residence in itself; an apartment taking up a whole floor. In this latter sense, the usage is more common in British English. [ 1913 Webster +PJC ]

6. (Mining) A horizontal vein or ore deposit auxiliary to a main vein; also, any horizontal portion of a vein not elsewhere horizontal. Raymond. [ 1913 Webster ]

7. A dull fellow; a simpleton; a numskull. [ Colloq. ] [ 1913 Webster ]

Or if you can not make a speech,
Because you are a flat. Holmes. [ 1913 Webster ]

8. (Mus.) A character [ ♭ ] before a note, indicating a tone which is a half step or semitone lower. [ 1913 Webster ]

9. (Geom.) A homaloid space or extension. [ 1913 Webster ]

v. t. [ imp. & p. p. Flatted p. pr. & vb. n. Flatting ] 1. To make flat; to flatten; to level. [ 1913 Webster ]

2. To render dull, insipid, or spiritless; to depress. [ 1913 Webster ]

Passions are allayed, appetites are flatted. Barrow. [ 1913 Webster ]

3. To depress in tone, as a musical note; especially, to lower in pitch by half a tone. [ 1913 Webster ]

a. [ Compar. Flatter superl. Flattest ] [ Akin to Icel. flatr, Sw. flat, Dan. flad, OHG. flaz, and AS. flet floor, G. flötz stratum, layer. ] 1. Having an even and horizontal surface, or nearly so, without prominences or depressions; level without inclination; plane. [ 1913 Webster ]

Though sun and moon
Were in the flat sea sunk. Milton. [ 1913 Webster ]

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. [ 1913 Webster ]

What ruins kingdoms, and lays cities flat! Milton. [ 1913 Webster ]

I feel . . . my hopes all flat. Milton. [ 1913 Webster ]

3. (Fine Arts) Wanting relief; destitute of variety; without points of prominence and striking interest. [ 1913 Webster ]

A large part of the work is, to me, very flat. Coleridge. [ 1913 Webster ]

4. Tasteless; stale; vapid; insipid; dead; as, fruit or drink flat to the taste. [ 1913 Webster ]

5. Unanimated; dull; uninteresting; without point or spirit; monotonous; as, a flat speech or composition. [ 1913 Webster ]

How weary, stale, flat, and unprofitable
Seem to me all the uses of this world. Shak. [ 1913 Webster ]

6. Lacking liveliness of commercial exchange and dealings; depressed; dull; as, the market is flat. [ 1913 Webster ]

7. Clear; unmistakable; peremptory; absolute; positive; downright.
Syn. -- flat-out. [ 1913 Webster ]

Flat burglary as ever was committed. Shak. [ 1913 Webster ]

A great tobacco taker too, -- that's flat. Marston. [ 1913 Webster ]

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. [ 1913 Webster ]

9. (Phonetics) Sonant; vocal; -- applied to any one of the sonant or vocal consonants, as distinguished from a nonsonant (or sharp) consonant. [ 1913 Webster ]

10. (Golf) Having a head at a very obtuse angle to the shaft; -- said of a club. [ Webster 1913 Suppl. ]

11. (Gram.) Not having an inflectional ending or sign, as a noun used as an adjective, or an adjective as an adverb, without the addition of a formative suffix, or an infinitive without the sign to. Many flat adverbs, as in run fast, buy cheap, are from AS. adverbs in -ë, the loss of this ending having made them like the adjectives. Some having forms in ly, such as exceeding, wonderful, true, are now archaic. [ Webster 1913 Suppl. ]

12. (Hort.) Flattening at the ends; -- said of certain fruits. [ Webster 1913 Suppl. ]

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. 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. [ 1913 Webster ] Of all who fell by saber or by shot,
Not one fell half so flat as Walter Scott. Lord Erskine. [ 1913 Webster ]

v. i. 1. To become flat, or flattened; to sink or fall to an even surface. Sir W. Temple. [ 1913 Webster ]

2. (Mus.) To fall form the pitch. [ 1913 Webster ]

To flat out, to fail from a promising beginning; to make a bad ending; to disappoint expectations. [ Colloq. ] [ 1913 Webster ]

adv. 1. In a flat manner; directly; flatly. [ 1913 Webster ]

Sin is flat opposite to the Almighty. Herbert. [ 1913 Webster ]

2. (Stock Exchange) Without allowance for accrued interest. [ Broker's Cant ] [ 1913 Webster ]

n. (Zool.) Any bird of the genus Flatyrynchus. They belong to the family of flycatchers. [ 1913 Webster ]

n. A boat with a flat bottom and square ends; -- used for the transportation of bulky freight, especially in shallow waters. [ 1913 Webster ]

a. Having an even lower surface or bottom; as, a flat-bottomed boat. [ 1913 Webster ]

adj. 1. having a flat bottom. a flat-bottom boat [ WordNet 1.5 ]

n. A kind of low-crowned cap formerly worn by all classes in England, and continued in London after disuse elsewhere; -- hence, a citizen of London. Marston. [ 1913 Webster ]