from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Having a horizontal surface without a slope, tilt, or curvature.
  • adj. Having a smooth, even, level surface: a skirt sewed with fine flat seams.
  • adj. Having a relatively broad surface in relation to thickness or depth: a flat board. See Synonyms at level.
  • adj. Stretched out or lying at full length along the ground; prone.
  • adj. Free of qualification; absolute: a flat refusal.
  • adj. Fixed; unvarying: a flat rate.
  • adj. Lacking interest or excitement; dull: a flat scenario.
  • adj. Lacking in flavor: a flat stew that needs salt.
  • adj. Having lost effervescence or sparkle: flat beer.
  • adj. Deflated. Used of a tire.
  • adj. Electrically discharged. Used of a storage battery.
  • adj. Of or relating to a horizontal line that displays no ups or downs and signifies the absence of physiological activity: A flat electroencephalogram indicates a loss of brain function.
  • adj. Commercially inactive; sluggish: flat sales for the month.
  • adj. Unmodulated; monotonous: a flat voice.
  • adj. Lacking variety in tint or shading; uniform: "The sky was bright but flat, the color of oyster shells” ( Anne Tyler).
  • adj. Not glossy; mat: flat paint.
  • adj. Music Being below the correct pitch.
  • adj. Music Being one half step lower than the corresponding natural key: the key of B flat.
  • adj. Designating the vowel a as pronounced in bad or cat.
  • adj. Nautical Taut. Used of a sail.
  • adv. Level with the ground; horizontally.
  • adv. On or up against a flat surface; at full length.
  • adv. So as to be flat.
  • adv. Directly; completely: went flat against the rules; flat broke.
  • adv. Exactly; precisely: arrived in six minutes flat.
  • adv. Music Below the intended pitch.
  • adv. Business Without interest charge.
  • n. A flat surface or part.
  • n. A stretch of level ground. Often used in the plural: salt flats.
  • n. A shallow frame or box for seeds or seedlings.
  • n. A movable section of stage scenery, usually consisting of a wooden frame and a decorated panel of wood or cloth.
  • n. A flatcar.
  • n. A deflated tire.
  • n. A shoe with a flat heel.
  • n. A large flat piece of mail.
  • n. A horse that competes in a flat race. Also called runner.
  • n. Music A sign (♭) used to indicate that a note is to be lowered by a half step.
  • n. Music A note that is lowered a half step.
  • n. Football The area of the field to either side of an offensive formation.
  • transitive v. To make flat; flatten.
  • transitive v. Music To lower (a note) a semitone.
  • intransitive v. Music To sing or play below the proper pitch.
  • n. An apartment on one floor of a building.
  • n. Archaic A story in a house.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Having no variations in altitude.
  • adj. Deflated, especially because of a puncture.
  • adj. Lowered by one semitone.
  • adj. Of a note or voice, lower in pitch than it should be.
  • adj. Without variations in pitch.
  • adj. Of a carbonated drink, with all or most of its carbon dioxide having come out of solution so that the drink no longer fizzes or contains any bubbles.
  • adj. Uninteresting.
  • adj. Lacking acidity without being sweet.
  • adj. Absolute.
  • adj. Describing certain features, usually the breasts or buttocks, that are extremely small or not visible at all.
  • adj. Unable to generate power; dead.
  • adj. Without spin; spinless.
  • adv. So as to be flat.
  • adv. Bluntly.
  • adv. Not exceeding.
  • adv. Completely.
  • n. An area of level ground.
  • n. A note played a semitone lower than a natural, denoted by the symbol ♭ sign placed after the letter representing the note (e.g., B♭) or in front of the note symbol (e.g. ♭♪).
  • n. A flat tyre/tire.
  • n. A type of ladies' shoes with very low heels.
  • n. A thin, broad brush used in oil and watercolor/watercolour painting.
  • n. The flat part of something:
  • n. A wide, shallow container.
  • n. A subset of n-dimensional space that is congruent to a Euclidean space of lower dimension.
  • v. To make a flat call; to call without raising.
  • v. To become flat or flattened; to sink or fall to an even surface.
  • v. To fall from the pitch.
  • n. An apartment.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Having an even and horizontal surface, or nearly so, without prominences or depressions; level without inclination; plane.
  • adj. Lying at full length, or spread out, upon the ground; level with the ground or earth; prostrate; ; hence, fallen; laid low; ruined; destroyed.
  • adj. Wanting relief; destitute of variety; without points of prominence and striking interest.
  • adj. Tasteless; stale; vapid; insipid; dead.
  • adj. Unanimated; dull; uninteresting; without point or spirit; monotonous.
  • adj. Lacking liveliness of commercial exchange and dealings; depressed; dull.
  • adj. Clear; unmistakable; peremptory; absolute; positive; downright.
  • adj.
  • adj. Below the true pitch; hence, as applied to intervals, minor, or lower by a half step
  • adj. Not sharp or shrill; not acute.
  • adj. Sonant; vocal; -- applied to any one of the sonant or vocal consonants, as distinguished from a nonsonant (or sharp) consonant.
  • adj. Having a head at a very obtuse angle to the shaft; -- said of a club.
  • adj. 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.
  • adj. Flattening at the ends; -- said of certain fruits.
  • adv. In a flat manner; directly; flatly.
  • adv. Without allowance for accrued interest.
  • n. 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.
  • n. 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.
  • n. Something broad and flat in form.
  • n. A flat-bottomed boat, without keel, and of small draught.
  • n. A straw hat, broad-brimmed and low-crowned.
  • n. A car without a roof, the body of which is a platform without sides; a platform car.
  • n. A platform on wheel, upon which emblematic designs, etc., are carried in processions.
  • n. The flat part, or side, of anything; as, the broad side of a blade, as distinguished from its edge.
  • n. A floor, loft, or story in a building
  • n. A horizontal vein or ore deposit auxiliary to a main vein; also, any horizontal portion of a vein not elsewhere horizontal.
  • n. A dull fellow; a simpleton; a numskull.
  • n. A character [♭] before a note, indicating a tone which is a half step or semitone lower.
  • n. A homaloid space or extension.
  • intransitive v. To become flat, or flattened; to sink or fall to an even surface.
  • intransitive v. To fall form the pitch.
  • transitive v. To make flat; to flatten; to level.
  • transitive v. To render dull, insipid, or spiritless; to depress.
  • transitive v. To depress in tone, as a musical note; especially, to lower in pitch by half a tone.

from The Century Dictionary and Cyclopedia

  • 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.
  • To dash or throw.
  • To dash; rush.
  • 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.
  • n. A floor or story of a building. Hence, in recent general use
  • n. 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.
  • n. A blow.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. sounded or spoken in a tone unvarying in pitch
  • adj. lacking the expected range or depth; not designed to give an illusion or depth
  • n. scenery consisting of a wooden frame covered with painted canvas; part of a stage setting
  • n. a musical notation indicating one half step lower than the note named
  • adj. lacking taste or flavor or tang
  • n. a suite of rooms usually on one floor of an apartment house
  • n. freight car without permanent sides or roof
  • adj. having a relatively broad surface in relation to depth or thickness
  • adj. lacking contrast or shading between tones
  • adj. lacking stimulating characteristics; uninteresting
  • adv. with flat sails
  • adj. flattened laterally along the whole length (e.g., certain leafstalks or flatfishes)
  • adj. stretched out and lying at full length along the ground
  • adj. not modified or restricted by reservations
  • adj. not reflecting light; not glossy
  • adj. horizontally level
  • n. a deflated pneumatic tire
  • adj. commercially inactive
  • adj. having lost effervescence
  • adj. (of a musical note) lowered in pitch by one chromatic semitone
  • n. a shallow box in which seedlings are started
  • n. a level tract of land
  • adv. in a forthright manner; candidly or frankly
  • adj. having a surface without slope, tilt in which no part is higher or lower than another


from The American Heritage® Dictionary of the English Language, 4th Edition

Middle English, from Old Norse flatr; see plat- in Indo-European roots.
Alteration of Scots flet, inner part of a house, from Middle English, from Old English, floor, dwelling; see plat- in Indo-European roots.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Old Norse flatr (Swedish flat, Danish flad), akin to German Flöz (geological layer), Ancient Greek πλατύς, Latvian plats, Sanskrit प्रत्हस् ("extension").

from Wiktionary, Creative Commons Attribution/Share-Alike License

1795, alteration of Scots flet ("inner part of a house"), from Middle English flet ("dwelling"), from Old English flet, flett ("ground floor, dwelling"), from Proto-Germanic *flajan (“floor”), from Proto-Germanic *flataz (“flat”), from Proto-Indo-European *plat- (“flat”). Akin to Old Frisian flet, flette "dwelling, house". More at flat1.


  • To summarize my previous comment, the LT data does not track surface temperature at all well – the LT temperature trend is essentially flat from ~1978 to ~1998, then there is the large 1998 El Nino spike and reversal, and then a ~0.2C step-up which has stayed ~flat for the most recent ~5 years.

    Trip Report « Climate Audit

  • Now if, _at the present moment_, this skein were cut with a straight knife at right angles to its length, the cut end would represent the _time plane_ -- that is, the present moment of all -- and it would be the same for all providing that the time plane were flat _But is it really flat_?

    Four-Dimensional Vistas

  • V. i.112 (241,5) [as fat and fulsome] [W: flat] _Fat_ means _dull_; so we say a _fatheaded_ fellow; _fat_ likewise means _gross_, and is sometimes used for _obscene_; and _fat_ is more congruent to _fulsome_ than _flat_.

    Notes to Shakespeare — Volume 01: Comedies

  • The term "flat tax" has "almost become a catchphrase for simplifying the tax code," Verenda Smith, senior manager of administration and policy for the Federation of Tax Administrators, cautioned.

    Yahoo! News: Business - Opinion

  • Any exemptions, deductions, differential rates, or progressivity would, as a matter of linguistics, preclude the name flat tax.


  • (Art. Apartment House), the term flat “is usually in the United States restricted to apartments in houses having no elevator or hall service.

    Chapter 4. American and English Today. 2. Differences in Usage

  • I use the term flat-earther for those who deny that the UK climate has changed over the past two centuries, and in particular since 1970.


  • Usually the term flat tax refers to household income (and sometimes corporate profits) being taxed at one marginal rate, in contrast with progressive taxes that vary according to parameters such as income or usage levels.

    Propeller Most Popular Stories

  • The jump start provided by Reynolds 'first round-tripper of the year was a much needed shot in the arm for a squad that defined the term flat Friday, according to head coach Rob Coddington.

  • This does not further the debate and I apologise to all for that last rant, including Mr. Porritt who I'm sure is a very nice chap. However when the term flat earth or denialist is used my hackles to tend to get rather raised. - home


Log in or sign up to get involved in the conversation. It's quick and easy.