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

There was—and is—something definitely wrong with Russell’s car, which was clearly slower than its sister car on several flat-out sections. — Jonathan M. Gitlin, ArsTechnica, 20 July 2026

Teams will likely veer more toward low-downforce wings in order to maximize the flat-out sections, with five Straight Mode zones to also help them along the way. — Madeline Coleman, New York Times, 15 July 2026

Adverb

The market up until now has been looking through or flat out ignoring the inevitable supply shock if the status quo persists, our base case expectation. — Brian Sullivan, CNBC, 23 July 2026

Because the hybrid side of the new power units provides such little energy, going flat out all the time is not the fastest way to complete a lap. — Jonathan M. Gitlin, ArsTechnica, 20 July 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