Lying all in one plane; without rotundity, curvature, or other variation or inequality; plane; specifically, in mathematics, having no curvature; homaloidal; having the locus of infinitely distant points linear: applied to space of any number of dimensions. In the common use of the word, levelness or horizontalness is often implied.Prostrate; lying the whole length on the ground; level with the ground; hence, fallen; laid low; ruined.Having little or no relief; deficient in prominence or roundness of figure or feature; lacking contrast in appearance, whether physical or visual; smooth; even; without shading: as, flat tints; a flat painting; a flat face, nose, or head; flat cheeks.Having no definite or characteristic taste; tasteless; stale; vapid; insipid; dead.Having little or no interest or attractive quality; without briskness or animation; lacking activity; stupid; dull.Not relieved, broken, or softened by qualifications or conditions; peremptory; absolute; positive; downright.Not clear, precise, or sonorous: as, a flat sound or accent.In music: Of tones, below a given or intended pitch.Of intervals, minor; diminished: as, a flat fifth.Of keys or tonalities, having flats in the signature: as, the key of F is a flat key.In grammar, voiced or sonant: said of consonants, such as b, d, g, z, v: opposed to sharp (that is, breathed or surd) consonants, such as p, t, k, s, f.On the stock exchange, without interest: applied to stocks when no interest is allowed by a lender of them on the sum deposited with him as security for their return when the purpose for which the stock was borrowed has been accomplished: such stock is said to be borrowed flat.Synonyms Level, Flat. See level.n. A flat surface; a surface without curvature or inequality; especially, a level plain; a field.n. A level ground near water or covered by shallow water; a shoal or sand-bank; specifically, in the United States, a low alluvial plain near tide-water or along a river, as the Jersey (United States) or Mohawk flats; also, the part of a shore that is uncovered at low tide.n. The flat part or side of anything, as the extended palm and fingers of the hand, the broad side of a sword or knife, the part of a panel included by the beading or molding, etc.: as, to strike with the flat of the hand, or of a sword.n. Something broad and flat in form, or presenting a broad flat surface as a characteristic feature.n. A foolish person; a simpleton; one who is easily duped; a gull.n. In architecture: See flat.n. A horizontal or approximately horizontal roof, usually, in northern climates, covered with lead or tin.n. In music: A tone one half-step below a given tone: as, the flat of B—that is, B flat.n. On the pianoforte, with reference to any-given key, the key next below or to the left.n. In musical notation, the character b, which when attached to a note or to a staff-degree lowers its significance one half-step. See B rotundum, under B.n. In ship-building, formerly, one of the midship timbers.n. In theaters, one of the halves of such scenes or parts of scenes as are formed by two equal parts pushed from the sides of the stage and meeting in the center.n. In mining, in the lead-mining districts of the north of England, a lateral branching of the vein, which gives rise to a deposit, as of ore, in flat masses.n. A surface of size put over gilding.n. A continuum of any number of dimensions having no curvature: such are a straight line, a plane, and Euclidean space.n. Flat opposition or contradiction; a point-blank assertion or denial.n. On the pianoforte, a key next but one below or to the left of a given key.n. The character bb, which when attached to a note or to a staff'-degree lowers its significance two half-steps.To make flat; level or bring to a level; lay even; make smooth; flatten.To level with the ground; overthrow.To make vapid or tasteless.In music, to depress (a tone); specifically, to apply a flat to (a note or staff-degree)—that is, to depress it a half-step. Also flatten.To decorate or paint with colors ground in linseed-oil, and thinned for use with turpentine. The turpentine kills the gloss of the oil, and the resulting surface appears dull or flat.To become flat; fall to an even surface.To become insipid, or dull and unanimated.In music, to sing or play below the true pitch. Also flatten.Flatly; so as to be flat or level.Plainly; positively.In music, below the true pitch.n. A floor or story of a building. Hence, in recent general usen. A floor, or separate division of a floor, fitted for housekeeping and designed to be occupied by a single family; an apartment. Compare apartment-house.n. A building the various floors of which are fitted up as flats.To dash or throw.To dash; rush.n. A blow.To flatter.In cotton-shipping, not compressed; not hard packed.In printing, said of the proof or print of a plate or engraving in relief which has received the flat impression of the press without the overlay used to develop light, shade, and perspective.In golf, said of the lie of a club, when the head is at a very obtuse angle to the shaft.Not distinguished by a characteristic termination: as, a flat adjective (a noun that occupies an adjectival position before another noun and becomes an adjective without inflection or modification of form: as, a stone wall; garden flowers); a flat adverb (see adverb).n. n. In ship-building: A platform, deck, or floor which is of restricted area and does not form an important part of the vessel's structure.n. A narrow bar of iron or wood, covered with card-clothing, surmounting the main cylinder of a cotton-carding machine.n. In horticulture, a shallow box, usually 2 to 4 inches deep, used by gardeners to start seeds and cuttings, and also to serve as a tray on which to carry pots.In leather manufacturing, to shave or smooth on the flesh side.