flat-out

1 of 2

adjective

ˈflat-ˌau̇t 

1

: being or going at maximum effort or speed

2

: out-and-out, downright

It was a flat-out lie.

flat out

2 of 2

adverb

1

: in a blunt and direct manner : openly

… called flat out for revolution.

—National Review

2

: at top speed or peak performance

the car does 180 m.p.h. flat out

3

usually flat-out

ˈflat-ˌau̇t 

: absolutely, downright

—usually used as an intensive

is just flat-out confusing

Synonyms of flat-out

Adjective

• utter
• sheer
• absolute
• unconditional
• outright
• complete
• pure
• simple
• total
• definite
• damned
• damn
• downright
• perfect
• very

Examples of flat-out in a Sentence

Adjective

regarded their son-in-law as a flat-out loser and let him know it

Adverb

I told him flat out that I have no intention of marrying him.

We asked for more time but they refused us flat out.

The car does 180 mph flat out.

Recent Examples on the Web

Adjective

The singer refused to flat-out say the Eagles are calling it quits. —Thor Christensen, Dallas Morning News, 11 Feb. 2026

But this new investigation shows a much broader swath of patients being surveilled by hospitals, child welfare authorities and law enforcement than previously known — even while the underlying evidence for those allegations is unreliable, easy to misinterpret and sometimes flat-out wrong. —Shoshana Walter, CBS News, 10 Feb. 2026

Adverb

If a 17-game schedule is too much from a player safety standpoint, 18 is flat out overkill. —Jim Alexander, Oc Register, 6 Feb. 2026

Except that the answer is wholly insufficient, and worse than that, flat out incorrect. —John Tamny, Forbes.com, 26 Jan. 2026

Word History

First Known Use

Adjective

1906, in the meaning defined at sense 1

Adverb

1932, in the meaning defined at sense 1

Rhymes for flat-out

• about
• bailout
• blackout
• blowout
• breakout
• burnout
• buyout
• checkout
• closeout
• cutout
• devout
• dropout