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• flat-out
  flat-out

  adjective

  moving or working at top speed or with maximum effort; all-out.
• flat out
  flat out

  In a direct manner, bluntly. For example, He told the true story flat out . [ Colloquial ; mid-1900s]

flat-out

American  

[flat-out] / ˈflætˈaʊt /

adjective

Informal.

1. moving or working at top speed or with maximum effort; all-out.

   a flat-out effort by all contestants.

2. downright; thoroughgoing.

   Many of the paintings were flat-out forgeries.

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flat out Idioms  

1. In a direct manner, bluntly. For example, He told the true story flat out . [ Colloquial ; mid-1900s]

2. At top speed, as in She was running flat out to catch the train . [ Slang ; c. 1930]

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Etymology

Origin of flat-out

First recorded in 1925–30

Example Sentences

Or its reply is flat-out wrong on an opinion query like, “What’s your favorite ice cream?”

From The Wall Street Journal • May 21, 2026

Animal activists noted that CNMI's new guidelines fell short of the flat-out bans on fur seen in other fashion weeks, but nevertheless called it progress.

From Barron's • May 15, 2026

In any case, the rate of hiring this year is a big improvement over last fall, when the economy was flat-out losing jobs.

From MarketWatch • May 7, 2026

But Bill Sutherland, a biologist at the University of Cambridge, has found that some dogma in conservation is flat-out wrong when put to the test.

From Slate • Apr. 28, 2026

One night, when we had turned the lights off, he flat-out asked what I was doing in the Academy.

From "Newjack: Guarding Sing Sing" by Ted Conover