"Flat" is a word in LAW AND LEGAL, ENGLISH

A place covered with water too shallow for navigation with vessels ordinarily used for commercial purposes. The space between high and low water mark along the edge of an arm of the sea, bay, tidal river, etc. Thomas v. Hatch, 23 Fed. Cas. 946; Church v. Meeker, 34 Conn. 424; Jones v. Janney, 8 watts & S. (Pa.) 443, 42 Am. Dec. 309

A flat-bottomed boat, without keel, and of small draught.

A straw hat, broad-brimmed and low-crowned.

In a flat manner; directly; flatly.

To become flat, or flattened; to sink or fall to an even
surface.

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.

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

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

To render dull, insipid, or spiritless; to depress.

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

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.

A platform on wheel, upon which emblematic designs, etc., are
carried in processions.

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.

A car without a roof, the body of which is a platform without
sides; a platform car.

Having an even and horizontal surface, or nearly so,
without prominences or depressions; level without inclination; plane.

A dull fellow; a simpleton; a numskull.

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

Below the true pitch; hence, as applied to intervals,
minor, or lower by a half step; as, a flat seventh; A flat.

A horizontal vein or ore deposit auxiliary to a main vein;
also, any horizontal portion of a vein not elsewhere horizontal.

The flat part, or side, of anything; as, the broad side of a
blade, as distinguished from its edge.

To depress in tone, as a musical note; especially, to
lower in pitch by half a tone.

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

A homaloid space or extension.

To fall form the pitch.

Not sharp or shrill; not acute; as, a flat sound.

Wanting relief; destitute of variety; without points of
prominence and striking interest.

To make flat; to flatten; to level.

Something broad and flat in form

A character [/] before a note, indicating a tone which is a
half step or semitone lower.

Without allowance for accrued interest.

A floor, loft, or story in a building; especially, a floor of
a house, which forms a complete residence in itself.