Plane vs. Flat — What's the Difference?
By Tayyaba Rehman & Maham Liaqat — Updated on April 5, 2024
Plane refers to a level surface extending infinitely in all directions, often used in geometry, while flat denotes a smooth, even surface without bumps or depressions, commonly used in everyday contexts.
Difference Between Plane and Flat
Table of Contents
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Key Differences
A plane in geometry is an abstract concept representing a surface with zero curvature, extending infinitely in all dimensions. On the other hand, flat describes a physical surface's characteristic of being level and smooth, applicable to tangible objects.
While a plane is a theoretical construct used to explain and visualize geometric principles, flat surfaces are observed and interacted with in the real world, such as flat tables or floors.
In mathematics, the concept of a plane is fundamental in discussing and understanding shapes, angles, and dimensions. Conversely, flat is a descriptor that can apply to various real-life scenarios, from flat landscapes to the texture of a wall.
The term plane is also used in other contexts, such as in carpentry, where a planer creates a plane surface by shaving off material to make it flat. Meanwhile, flat can describe not just physical qualities but also qualities like flat soda, which lacks bubbles, indicating the term's broader applicability.
Planes are idealized representations, crucial for theoretical explorations and problem-solving in fields like geometry and physics. In contrast, flatness is a practical attribute that affects functionality and aesthetics in everyday objects and environments.
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Comparison Chart
Definition
A level surface with no curvature, extending infinitely
A smooth, even surface without bumps
Context
Geometry, theoretical
Real-world, tangible objects
Application
Used in explaining geometric principles
Describes physical characteristics
Examples
Geometric planes in mathematics
Flat landscapes, surfaces
Relevance
Theoretical constructs
Practical, observable attributes
Compare with Definitions
Plane
A theoretical surface with zero curvature.
A geometric plane extends infinitely in all directions without any bounds.
Flat
Used in various contexts, from geography to music.
The plains offer a remarkably flat landscape for miles.
Plane
Represents an idealized level surface in mathematics.
Planes are crucial in visualizing complex geometric concepts.
Flat
Describes a surface that is level and smooth.
They needed a flat surface to roll out the dough.
Plane
Applied in physics to explain concepts like motion.
Motion in a plane is studied to understand two-dimensional dynamics.
Flat
Describes the simplicity in design or feature.
The flat interface of the app made navigation very intuitive.
Plane
Can be made physically in carpentry or metalwork.
A carpenter uses a planer to create a plane surface on a piece of wood.
Flat
Indicates the absence of carbonation in beverages.
After being left open overnight, the soda went flat.
Plane
Used in geometry to discuss shapes and angles.
The angle between two lines is determined by their intersection on a plane.
Flat
Can refer to lack of volume or excitement.
The party was flat, lacking energy and enthusiasm.
Plane
(Mathematics) A surface containing all the straight lines that connect any two points on it.
Flat
Having a level surface; without raised areas or indentations
He sat down on a flat rock
Trim the surface of the cake to make it completely flat
Plane
A flat or level surface.
Flat
Lacking emotion; dull and lifeless
‘I'm sorry,’ he said, in a flat voice
Plane
A level of development, existence, or achievement
Scholarship on a high plane.
Flat
(of a sparkling drink) having lost its effervescence
She sipped some of the flat champagne
Plane
An airplane or hydroplane.
Flat
(of a fee, wage, or price) the same in all cases, not varying with changed conditions or in particular cases
A flat fare of £2.50
Plane
A supporting surface of an airplane; an airfoil or wing.
Flat
(of musical sound) below true or normal pitch.
Plane
A carpenter's tool with an adjustable blade for smoothing and leveling wood.
Flat
Relating to flat racing
The Flat season
Plane
A trowel-shaped tool for smoothing the surface of clay, sand, or plaster in a mold.
Flat
In or to a horizontal position
She had been knocked flat by the blast
He was lying flat on his back
Plane
The plane tree.
Flat
Completely; absolutely
I thought you'd turn me down flat
Myers was flat broke
Plane
(Mathematics) Of or being a figure lying in a plane
A plane curve.
Flat
Below the true or normal pitch of musical sound
It wasn't a question of singing flat, but of simply singing the wrong notes
Plane
Flat; level.
Flat
The flat part of something
She placed the flat of her hand over her glass
Plane
To smooth or finish with a plane
Planed the door.
Flat
An upright section of stage scenery mounted on a movable frame.
Plane
To remove with a plane
Plane off the rough edges on a board.
Flat
A flat tyre
I've got a flat—there were nails under the wheel
Plane
To work with a plane.
Flat
Flat racing.
Plane
To rise partly out of the water, as a hydroplane does at high speeds.
Flat
A musical note lowered a semitone below natural pitch.
Plane
To soar or glide.
Flat
A set of rooms forming an individual residence, typically on one floor and within a larger building containing a number of such residences.
A block of flats
Plane
To travel by airplane.
Flat
Lower (a note) by a semitone
‘blue’ harmony emphasizing the flatted third and seventh
Plane
Of a surface: flat or level.
Flat
Make flat; flatten
Flat the loaves down
Plane
A level or flat surface.
Flat
Live in or share a flat
Zoë flats in Auckland
Plane
(geometry) A flat surface extending infinitely in all directions (e.g. horizontal or vertical plane). Category:en:Surfaces
Flat
Having a smooth, even surface
A flat field.
Plane
(anatomy) An imaginary plane which divides the body into two portions.
Flat
Having a relatively broad level surface in relation to thickness or depth
A flat box.
Plane
A level of existence or development.
Astral plane
Flat
Being in horizontal position; lying down
Flat on his back.
Plane
A roughly flat, thin, often moveable structure used to create lateral force by the flow of air or water over its surface, found on aircraft, submarines, etc. (Compare airfoil, hydrofoil.)}}
Flat
Being without slope or curvature
A flat line on a chart.
Plane
Any of 17 designated ranges of 216 (65,536) sequential code points each.
Flat
Having a low heel or no heel
Flat shoes.
Plane
A tool for smoothing wood by removing thin layers from the surface.
Flat
Free of qualification; absolute
A flat refusal.
Plane
An airplane; an aeroplane.
Flat
Fixed; unvarying
A flat rate.
Plane
(entomology) Any of various nymphalid butterflies, of various genera, having a slow gliding flight.
Flat
Lacking interest or excitement; dull
A flat scenario.
Plane
(entomology) The butterfly Bindahara phocides, family Lycaenidae, of Asia and Australasia.
Flat
Lacking in flavor
A flat stew that needs salt.
Plane
(countable) A deciduous tree of the genus Platanus.
Flat
Having lost effervescence or sparkle
Flat beer.
Plane
(Northern UK) A sycamore.
Flat
Deflated. Used of a tire.
Plane
To smooth (wood) with a plane.
Flat
Electrically discharged. Used of a storage battery.
Plane
To move in a way that lifts the bow out of the water.
Flat
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.
Plane
To glide or soar.
Flat
Of or relating to a hierarchy with relatively few tiers or levels
A flat organization chart.
Plane
Any tree of the genus Platanus.
Flat
Commercially inactive; sluggish
Flat sales for the month.
Plane
A surface, real or imaginary, in which, if any two points are taken, the straight line which joins them lies wholly in that surface; or a surface, any section of which by a like surface is a straight line; a surface without curvature.
Flat
Unmodulated; monotonous
A flat voice.
Plane
An ideal surface, conceived as coinciding with, or containing, some designated astronomical line, circle, or other curve; as, the plane of an orbit; the plane of the ecliptic, or of the equator.
Flat
Lacking variety in tint or shading; uniform
"The sky was bright but flat, the color of oyster shells" (Anne Tyler).
Plane
A block or plate having a perfectly flat surface, used as a standard of flatness; a surface plate.
Flat
Not glossy; matte
Flat paint.
Plane
A tool for smoothing boards or other surfaces of wood, for forming moldings, etc. It consists of a smooth-soled stock, usually of wood, from the under side or face of which projects slightly the steel cutting edge of a chisel, called the iron, which inclines backward, with an apperture in front for the escape of shavings; as, the jack plane; the smoothing plane; the molding plane, etc.
Flat
Being below the correct pitch.
Plane
Without elevations or depressions; even; level; flat; lying in, or constituting, a plane; as, a plane surface.
Flat
Being one half step lower than the corresponding natural key
The key of B flat.
Plane
To make smooth; to level; to pare off the inequalities of the surface of, as of a board or other piece of wood, by the use of a plane; as, to plane a plank.
Flat
Designating the vowel a as pronounced in bad or cat.
Plane
To efface or remove.
He planed away the names . . . written on his tables.
Flat
(Nautical) Taut. Used of a sail.
Plane
Figuratively, to make plain or smooth.
What student came but that you planed her path.
Flat
Level with the ground; horizontally.
Plane
Of a boat, to lift more or less out of the water while in motion, after the manner of a hydroplane; to hydroplane.
Flat
On or up against a flat surface; at full length.
Plane
An aircraft that has a fixed wing and is powered by propellers or jets;
The flight was delayed due to trouble with the airplane
Flat
So as to be flat.
Plane
(mathematics) an unbounded two-dimensional shape;
We will refer to the plane of the graph as the X-Y plane
Any line joining two points on a plane lies wholly on that plane
Flat
Directly; completely
Went flat against the rules.
Flat broke.
Plane
A level of existence or development;
He lived on a worldly plane
Flat
Exactly; precisely
Arrived in six minutes flat.
Plane
A power tool for smoothing or shaping wood
Flat
(Music) Below the intended pitch.
Plane
A carpenter's hand tool with an adjustable blade for smoothing or shaping wood;
The cabinetmaker used a plane for the finish work
Flat
(Business) Without interest charge.
Plane
Cut or remove with or as if with a plane;
The machine shaved off fine layers from the piece of wood
Flat
A flat surface or part.
Plane
Travel on the surface of water
Flat
Often flats A stretch of level ground
Salt flats.
Plane
Make even or smooth, with or as with a carpenter's plane;
Plane the top of the door
Flat
A shallow frame or box for seeds or seedlings.
Plane
Having a horizontal surface in which no part is higher or lower than another;
A flat desk
Acres of level farmland
A plane surface
Flat
A movable section of stage scenery, usually consisting of a wooden frame and a decorated panel of wood or cloth.
Flat
A flatcar.
Flat
A deflated tire.
Flat
A shoe with a flat heel.
Flat
A large flat piece of mail.
Flat
A horse that competes in a flat race. Also called runner.
Flat
A sign (♭) used to indicate that a note is to be lowered by a semitone.
Flat
A note that is lowered a semitone.
Flat
(Football) The area of the field to either side of an offensive formation.
Flat
An apartment on one floor of a building.
Flat
(Archaic) A story in a house.
Flat
To make flat; flatten.
Flat
(Music) To lower (a note) a semitone.
Flat
To sing or play below the proper pitch.
Flat
Having no variations in height.
The land around here is flat.
Flat
In a horizontal line or plane; not sloping.
A flat roof
Flat
Smooth; having no protrusions, indentations or other surface irregularities, or relatively so.
The surface of the mirror must be completely flat.
The carpet isn't properly flat in that corner.
She has quite a flat face.
Flat
Without variation in level, quantity, value, tone etc.
The exchange rate has been flat for several weeks.
Flat
At a consistently depressed level; consistently lacklustre.
Sales have been flat all year, and we've barely broken even.
Flat
Of fees, fares etc., fixed; unvarying.
A flat fee
Flat rates
A flat fare on public transport
Flat
Without variations in pitch.
He delivered the speech in a flat tone.
Flat
(of colours) Without variation in tone or hue (uniform), and dull (not glossy).
The walls were painted a flat gray.
Flat
(figurative) Lacking liveliness or action; depressed; uninteresting; dull and boring.
The party was a bit flat.
The market is flat today as most traders are on holiday.
The dialogue in your screenplay is flat — you need to make it more exciting.
Flat
Lacking in depth, substance, or believability; underdeveloped; one-dimensional.
The author added a chapter to flesh out the book's flatter characters.
Flat
Lowered by one semitone.
Flat
(music) Of a note or voice, lower in pitch than it should be.
Your A string is flat.
Flat
Absolute; downright; peremptory.
His claim was in flat contradiction to experimental results.
I'm not going to the party and that's flat.
Flat
(of a tire or other inflated object) Deflated, especially because of a puncture.
Flat
(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.
Flat
(wine) Lacking acidity without being sweet.
Flat
(of a battery) Unable to emit power; dead.
Flat
Without spin; spinless.
Flat
Sonant; vocal, as distinguished from a sharp (non-sonant) consonant.
Flat
(grammar) Not having an inflectional ending or sign, such 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', etc. are from Old English.
Flat
Having a head at a very obtuse angle to the shaft.
Flat
Flattening at the ends.
Flat
(of measurements of time) Exact.
He finished the race in a flat four minutes.
Flat
So as to be flat.
Spread the tablecloth flat over the table.
Flat
Bluntly.
I asked him if he wanted to marry me and he turned me down flat.
Flat
(of accurately measured timings) Exactly, precisely.
In the mile race, Smith's time was 3:58.56, and Brown's was four minutes flat.
Flat
Used to emphasize the smallness of the measurement.
He can run a mile in four minutes flat.
Flat
Completely.
I am flat broke this month.
Flat
Directly; flatly.
Flat
Without allowance for accrued interest.
The bonds are trading flat.
Flat
An area of level ground (sometimes covered with water).
The hovercraft skimmed across the open flats.
The eastern end of the salt flat; mud flat, tidal flat, flood flat
Flat
(in the phrase 'the flat') Level ground in general.
I can run on the flat but not up hills.
The going will be easier once we're through these mountains and onto the flat.
Flat
Level horse-racing ground, as contrasted with courses incorporating jumps, or the racing done on such ground.
This horse will do better over the flat.
Flat racing, the flat season
Flat
The area in the centre of a racecourse.
Flat
(music) A note played a semitone lower than a natural, denoted by the symbol ♭ placed after the letter representing the note (e.g., B♭) or in front of the note symbol (e.g. ♭♪).
The key of E♭ has three flats.
Flat
A flat tyre/flat tire.
Flat
(in the plural) A type of ladies' shoe with a very low heel.
She liked to walk in her flats more than in her high heels.
Flat
(in the plural) A type of flat-soled running shoe without spikes.
Flat
(painting) A thin, broad brush used in oil and watercolour painting.
Flat
The flat part of something:
Flat
(swordfighting) The flat side of a blade, as opposed to the sharp edge.
Flat
The palm of the hand, with the adjacent part of the fingers.
Flat
A wide, shallow container or pallet.
A flat of strawberries
Flat
(mail) A large mail piece measuring at least 8 1/2 by 11 inches, such as catalogs, magazines, and unfolded paper enclosed in large envelopes.
Flat
A railroad car without a roof, and whose body is a platform without sides; a platform car or flatcar.
Flat
A flat-bottomed boat, without keel, and of small draught.
Flat
(geometry) A subset of n-dimensional space that is congruent to a Euclidean space of lower dimension.
Flat
A straw hat, broad-brimmed and low-crowned.
Flat
A flat sheet for use on a bed.
Flat
(publishing) A flat, glossy children's book with few pages.
Flat
A platform on a wheel, upon which emblematic designs etc. are carried in processions.
Flat
(mining) A horizontal vein or ore deposit auxiliary to a main vein; also, any horizontal portion of a vein not elsewhere horizontal.
Flat
(technical, theatre, stagecraft) A rectangular wooden structure covered with masonite, lauan, or muslin, often produced in standard modules, that is used to build wall surfaces on stage. Flats can be painted and outfitted with doors and/or windows to depict a building or other part of a scene. It's a hard-surfaced alternative to a backcloth orbackdrop.
Flat
(entomology) Any of various hesperiid butterflies that spread their wings open when they land.
Flat
(historical) An early kind of toy soldier having a flat design.
Flat
(obsolete) A dull fellow; a simpleton.
Flat
(optics) A flat (i.e. plane) mirror
Flat
A cheater's die with the edges shaved to make certain rolls more likely.
Flat
An apartment, usually on one level and usually consisting of more than one room.
Flat
(poker slang) To make a flat call; to call without raising.
Flat
(intransitive) To become flat or flattened; to sink or fall to an even surface.
Flat
To fall from the pitch.
Flat
To depress in tone, as a musical note; especially, to lower in pitch by half a tone.
Flat
To make flat; to flatten; to level.
Flat
To render dull, insipid, or spiritless; to depress.
Flat
To beat or strike; pound
Flat
(transitive) To dash or throw
Flat
(intransitive) To dash, rush
Flat
Having an even and horizontal surface, or nearly so, without prominences or depressions; level without inclination; plane.
Though sun and moonWere in the flat sea sunk.
Flat
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!
I feel . . . my hopes all flat.
Flat
Wanting relief; destitute of variety; without points of prominence and striking interest.
A large part of the work is, to me, very flat.
Flat
Tasteless; stale; vapid; insipid; dead; as, fruit or drink flat to the taste.
Flat
Unanimated; dull; uninteresting; without point or spirit; monotonous; as, a flat speech or composition.
How weary, stale, flat, and unprofitableSeem to me all the uses of this world.
Flat
Lacking liveliness of commercial exchange and dealings; depressed; dull; as, the market is flat.
Flat
Clear; unmistakable; peremptory; absolute; positive; downright.
Flat burglary as ever was committed.
A great tobacco taker too, - that's flat.
Flat
Below the true pitch; hence, as applied to intervals, minor, or lower by a half step; as, a flat seventh; A flat.
Flat
Sonant; vocal; - applied to any one of the sonant or vocal consonants, as distinguished from a nonsonant (or sharp) consonant.
Flat
Having a head at a very obtuse angle to the shaft; - said of a club.
Flat
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.
Flat
Flattening at the ends; - said of certain fruits.
Of all who fell by saber or by shot,Not one fell half so flat as Walter Scott.
Flat
In a flat manner; directly; flatly.
Sin is flat opposite to the Almighty.
Flat
Without allowance for accrued interest.
Flat
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.
Envy is as the sunbeams that beat hotter upon a bank, or steep rising ground, than upon a flat.
Flat
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.
Half my power, this nightPassing these flats, are taken by the tide.
Flat
Something broad and flat in form
Flat
The flat part, or side, of anything; as, the broad side of a blade, as distinguished from its edge.
Flat
A floor, loft, or story in a building;
Flat
A horizontal vein or ore deposit auxiliary to a main vein; also, any horizontal portion of a vein not elsewhere horizontal.
Flat
A dull fellow; a simpleton; a numskull.
Or if you can not make a speech,Because you are a flat.
Flat
A character [$] before a note, indicating a tone which is a half step or semitone lower.
Flat
A homaloid space or extension.
Flat
To make flat; to flatten; to level.
Flat
To render dull, insipid, or spiritless; to depress.
Passions are allayed, appetites are flatted.
Flat
To depress in tone, as a musical note; especially, to lower in pitch by half a tone.
Flat
To become flat, or flattened; to sink or fall to an even surface.
Flat
To fall form the pitch.
Flat
A level tract of land
Flat
A shallow box in which seedlings are started
Flat
A musical notation indicating one half step lower than the note named
Flat
Freight car without permanent sides or roof
Flat
A deflated pneumatic tire
Flat
Scenery consisting of a wooden frame covered with painted canvas; part of a stage setting
Flat
A suite of rooms usually on one floor of an apartment house
Flat
Having a horizontal surface in which no part is higher or lower than another;
A flat desk
Acres of level farmland
A plane surface
Flat
Having no depth or thickness
Flat
Not modified or restricted by reservations;
A categorical denial
A flat refusal
Flat
Stretched out and lying at full length along the ground;
Found himself lying flat on the floor
Flat
Lacking contrast or shading between tones
Flat
Lowered in pitch by one chromatic semitone;
B flat
C sharp
Flat
Flattened laterally along the whole length (e.g., certain leafstalks or flatfishes)
Flat
Lacking taste or flavor or tang;
A bland diet
Insipid hospital food
Flavorless supermarket tomatoes
Vapid beer
Vapid tea
Flat
Lacking stimulating characteristics; uninteresting;
A bland little drama
A flat joke
Flat
Having lost effervescence;
Flat beer
A flat cola
Flat
Not increasing as the amount taxed increases
Flat
Not made with leavening;
Most flat breads are made from unleavened dough
Flat
Parallel to the ground;
A flat roof
Flat
Without pleats
Flat
Lacking the expected range or depth; not designed to give an illusion or depth;
A film with two-dimensional characters
A flat two-dimensional painting
Flat
(of a tire) completely or partially deflated
Flat
Not reflecting light; not glossy;
Flat wall paint
A photograph with a matte finish
Flat
Lacking variety in shading;
A flat unshaded painting
Flat
At full length;
He fell flat on his face
Flat
With flat sails;
Sail flat against the wind
Flat
Below the proper pitch;
She sang flat last night
Flat
Against a flat surface;
He lay flat on his back
Flat
In a forthright manner; candidly or frankly;
He didn't answer directly
Told me straight out
Came out flat for less work and more pay
Flat
Wholly or completely;
He is flat broke
Common Curiosities
What is a geometric plane?
A geometric plane is an abstract surface that extends infinitely in all directions with no curvature.
Can a plane be observed in the real world?
While planes are theoretical constructs, their properties can be approximated in real-world objects like a perfectly flat table.
Is a flat landscape the same as a geometric plane?
No, a flat landscape refers to an area with minimal elevation changes, while a geometric plane is a theoretical concept in geometry.
How can a surface be considered flat?
A surface is considered flat if it is level, smooth, and without any bumps or depressions.
What makes a beverage flat?
A beverage becomes flat when it loses its carbonation or effervescence, often due to being left open.
How do planes relate to mathematics and physics?
In mathematics and physics, planes are used to explain and visualize concepts like dimensions, shapes, and motions.
What does flat mean in music?
In music, flat refers to a pitch that is slightly lower in frequency than the standard.
Why is flatness important in manufacturing?
Flatness is crucial in manufacturing for ensuring the functionality and fit of components, affecting both assembly and performance.
What is the difference between flat and matte?
Flat and matte both describe surfaces without gloss, but matte often pertains to a specific texture or finish that diffuses light.
Is there a tool to measure flatness?
Yes, tools like spirit levels, surface plates, and electronic level sensors measure the flatness of surfaces.
Can a computer screen be described as flat?
Yes, a computer screen can be described as flat, especially in contrast to older, curved CRT monitors.
What role does flatness play in art?
Flatness in art can refer to a style that emphasizes two-dimensionality and avoids the illusion of depth.
How do architects and engineers use the concept of a plane?
Architects and engineers use the concept of a plane to design and analyze structures, ensuring balance and spatial organization.
What does a flat response mean in audio equipment?
A flat response in audio equipment indicates that the device reproduces sounds across all frequencies equally, without bias.
How is flat used in describing characters or stories?
A character or story is described as flat if it lacks depth, complexity, or development.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Maham Liaqat
