flat

1 of 4

adjective

ˈflat 

flatter; flattest

1

a

: lying at full length or spread out upon the ground : prostrate

The soldiers were lying flat on the ground.

b

: utterly ruined or destroyed

buildings flat from the blast

c

: resting with a surface against something

Push the chairs flat against the wall.

2

a

: having a continuous horizontal surface

the flat landscape of the prairie

b

: being or characterized by a horizontal line or tracing without peaks or depressions

a flat EEG

3

: having a relatively smooth or even surface

a flat computer disk

4

: arranged or laid out so as to be level or even

maps flat on the desk

5

a

: having the major surfaces essentially parallel and distinctly greater than the minor surfaces

a flat piece of wood

b

of a shoe heel : very low and broad

flat shoes for work

6

a

: clearly unmistakable

a flat denial

b(1)

: not varying : fixed

a flat rate

(2)

: having no fraction either lacking or in excess : exact

in a flat 10 seconds

(3)

of a frequency response : not varying significantly throughout its range

7

a

: lacking in animation, zest, or vigor : dull

He spoke in a flat, tired voice.

b

: lacking flavor : tasteless

The stew is too flat.

c

: lacking effervescence or sparkle

flat ginger ale

d

: commercially inactive

also : characterized by no significant rise or decline from one period to another

sales were flat

e

of a tire : lacking air : deflated

f

chiefly British, of a battery : dead sense 3c, discharged

8

a(1)

of a tone : lowered a half step in pitch

(2)

: lower than the proper pitch

b

of the vowel a : pronounced as in bad or bat

9

a

: having a low trajectory (see trajectory sense 1)

made a flat pass that was intercepted

b

of a tennis stroke : made so as to give little or no spin to the ball

10

: not having an inflectional ending

flat adverbs

11

of a sail : taut

12

a

: uniform in hue or shade

figures standing out against a background of flat wash

b

: having little or no illusion of depth

c

of a photograph or negative : lacking contrast

d

of lighting conditions : lacking shadows or contours

e

: free from gloss : having a nonreflective finish

a flat paint

f

: two-dimensional sense 3

flat characters

13

: of, relating to, or used in competition on the flat

a flat horse

14

of a universe : having a mass such that expansion halts only after infinite time and collapse never occurs

flatly adverb

flatness noun

flattish

ˈfla-tish 

adjective

flat

2 of 4

noun

1

a

: a level surface of land

—usually used in plural

sagebrush flats

tidal flats

b

: a stretch of land without obstacles

especially : a track or course for a flat race

—usually used with the

has won twice on the flat

2

: a flat part or surface

the flat of one's hand

3

a

: a musical note or tone one half step lower than a specified note or tone

b

: a character ♭ on a line or space of the musical staff indicating a half step drop in pitch

4

: something flat: such as

a

: a shallow container for shipping produce

b

: a shallow box in which seedlings are started

c

: a flat piece of theatrical scenery

d

: a shoe or slipper having a flat heel or no heel

5

chiefly British : an apartment on one floor

6

: a deflated tire

7

: the area to either side of an offensive football formation

flat

3 of 4

adverb

1

: in a flat manner : directly, positively

2

: in a complete manner : absolutely

flat broke

3

: below the proper musical pitch

4

: without interest charge

especially : without allowance or charge for accrued interest

bonds sold flat

flat

4 of 4

verb

flatted; flatting

transitive verb

1

: flatten

2

: to lower in pitch especially by a half step

intransitive verb

: to sing or play below the true pitch

Synonyms

Adjective

• exact
• round

Noun

• apartment

Adverb

• completely
• perfectly
• quite
• totally
• fully
• utterly
• fast
• all
• wide
• wholly
• well
• thoroughly
• entirely
• entire
• exactly
• even
• absolutely
• out

Choose the Right Synonym for flat

level, flat, plane, even, smooth mean having a surface without bends, curves, or irregularities.

level applies to a horizontal surface that lies on a line parallel with the horizon.

the vast prairies are nearly level

flat applies to a surface devoid of noticeable curvatures, prominences, or depressions.

the work surface must be flat

plane applies to any real or imaginary flat surface in which a straight line between any two points on it lies wholly within that surface.

the plane sides of a crystal

even applies to a surface that is noticeably flat or level or to a line that is observably straight.

trim the hedge so it is even

smooth applies especially to a polished surface free of irregularities.

a smooth skating rink

insipid, vapid, flat, jejune, banal, inane mean devoid of qualities that make for spirit and character.

insipid implies a lack of sufficient taste or savor to please or interest.

an insipid romance with platitudes on every page

vapid suggests a lack of liveliness, force, or spirit.

an exciting story given a vapid treatment

flat applies to things that have lost their sparkle or zest.

although well-regarded in its day, the novel now seems flat

jejune suggests a lack of rewarding or satisfying substance.

a jejune and gassy speech

banal stresses the complete absence of freshness, novelty, or immediacy.

a banal tale of unrequited love

inane implies a lack of any significant or convincing quality.

an inane interpretation of the play

Examples of flat in a Sentence

Adjective

the flat top of the table

the flat landscape of the prairie

Coins are usually round and flat.

a flat piece of wood

Noun

the flat of your hand

the flat of a sword

Adverb

Lay the map flat on the desk.

He slipped and landed flat on his back.

We asked for more time but they turned us down flat.

Recent Examples on the Web

Adjective

Its waterproof finish keeps the salty ocean spray away from your belongings, and its flat bottom stays upright on sand. —Caley Sturgill, People.com, 14 July 2025

Typically support is limited, either by a sole that’s too rigid to go flat, a sole that’s too flexible for a safe heel, or a mechanism that lacks the ability to swap the heels. —Yola Robert, Forbes.com, 14 July 2025

Noun

Our current favorite pairs include a few riffs on those flats from The Row—but thanks to the recent creative renaissance around jellies, there are so many more options to discover. —Jake Henry Smith, Glamour, 15 July 2025

The actress accessorized with a wicker handbag and white pointed-toe flats. —Catherine Santino, People.com, 14 July 2025

Adverb

Without real user demand, even the best monetization strategy will fall flat. —Expert Panel®, Forbes.com, 11 July 2025

Despite later becoming a pet for Superboy, the two never really vibe, and any attempts to install this incarnation as a mainstay fall flat. —Daniel Dockery, Vulture, 11 July 2025

Verb

Testers love the comfortable elastic waistband of the pants and the flatting scoop neck of the t-shirt. —Health Editorial Team, Health, 14 Mar. 2025

Stuart Weitzman Outlet: Enjoy an extra 25 percent off boots, pumps, and Mary Jane flats sitewide with code HELLO25 until January 2. —Averi Baudler, People.com, 26 Dec. 2024

Word History

Etymology

Adjective, Noun, Adverb, and Verb

Middle English, from Old Norse flatr; akin to Old High German flaz flat, and probably to Greek platys broad — more at place

First Known Use

Adjective

14th century, in the meaning defined at sense 1a

Noun

14th century, in the meaning defined at sense 1a

Adverb

1531, in the meaning defined at sense 1

Verb

circa 1604, in the meaning defined at transitive sense 1

Phrases Containing flat

• change a flat
• change a (flat) tire
• European flat
• European flat oyster
• fall flat
• flat as a pancake
• flat battery
• flat broke
• flat-coated retriever
• flat-earther
• flat-earthist
• flat-footed
• flat-hat
• flat iron
• flat on one's back
• flat out
• flat-panel
• flat-picking
• flat race
• flat-screen
• flat tax
• granny flat
• in nothing flat
• railroad flat
• salt flat
• studio flat

Rhymes for flat

• at
• bat
• batt
• brat
• cat
• chat
• fat
• gat
• gnat
• hat
• kat
• mat

Kids Definition

flat

1 of 4 adjective

flatter; flattest

1

: having a smooth level surface

flat ground

2

: having a smooth even surface

3

: spread out on or along a surface

was flat on the ground

4

: having a broad smooth surface and little thickness

shoes with flat heels

5

: absolute sense 3

a flat refusal

6

: fixed sense 1b, unchanging

charge a flat rate

7

: exact entry 2 sense 1

in two minutes flat

8

a

: lacking in interest or flavor

a flat story

the stew tastes flat

b

: lacking bubbles or sparkle

flat ginger ale

c

: lacking any rise or decline

sales were flat

9

: being deflated

—used of tires

10

a

: lower than the true pitch

b

: lower by a half step

tone of A flat

11

: free from gloss

flat paint

flatly adverb

flatness noun

flat

2 of 4 noun

ˈflat

1

: a level surface of land : plain

2

: a flat part or surface

3

a

: a musical tone one half step lower than a specified tone

b

: a character ♭ before a note indicating that it is to be a flat

4

: a shallow box in which seedlings are started

5

: a shoe or slipper having a flat heel or no heel

6

chiefly British : an apartment on one floor

7

: a deflated tire

flat

3 of 4 adverb

1

: on or against a flat surface

lie flat

2

: as much as possible : completely

was flat broke

3

: below the true musical pitch

flat

4 of 4 verb

flatted; flatting

: to lower in pitch especially by a half step

Medical Definition

flat

adjective

ˈflat 

flatter; flattest

1

: being or characterized by a horizontal line or tracing without peaks or depressions

the EEG is ominously flat indicating that her brain function is gone

—Don Gold

2

: characterized by general impoverishment in the presence of emotion-evoking stimuli

flat affect often occurs in schizophrenia

flatness noun

Legal Definition

flat

1 of 2 adjective

: not varying

a flat rate

specifically, of a tax : having a rate that remains constant for any taxable base

flat

2 of 2 adverb

: without interest charge

especially : without allowance or charge for accrued interest

bonds sold flat