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

Rose Byrne’s gonzo portrayal of a woman over the edge is flat-out brilliant, the most powerful thing she’s done and one of the best performances of the year. —Bill Goodykoontz, AZCentral.com, 24 Oct. 2025

Their offense lit up the scoreboard and their defense flat-out dominated. —Mike Jones, New York Times, 2 Oct. 2025

Adverb

That’s flat out a controllable that our team knows that keeps you from winning. —Barry Jackson, Miami Herald, 31 Oct. 2025

While some Christian creators seem to be taking the demonic allegations quite seriously, the Hatch backlash has become a bit of a meme online, with users accusing the women of being in religious psychosis or just flat out ridiculous. —Ct Jones, Rolling Stone, 29 Oct. 2025

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