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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

See Examples For:

flat-out flat out

When Eisenberg first met Moore, he told her flat-out, “I don’t want you to worry about this scene.”

From Los Angeles Times ● Sep. 7, 2026

As it turns out, I’m hardly the only person to have felt hoodwinked, bamboozled, and/or flat-out deceived by my smartphone’s forecasts in 2026.

From Slate ● Aug. 21, 2026

Given all that, it is flat-out wrong to say that AI adoption is stagnating, says Ethan Mollick, a Wharton professor who studies how companies adopt AI.

From The Wall Street Journal ● Jun. 7, 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

I couldn’t tell if she was poking fun at me or flat-out handing me an insult.

From "The Detective's Assistant" by Kate Hannigan

“This is flat out a lie,” responded Kalshi’s co-founder and operating chief, Luana Lopes Lara, less than a half-hour later.

From The Wall Street Journal ● Aug. 12, 2026

The track's most iconic corner, the flat-out swerves known as Eau Rouge, has been easily flat out on a qualifying lap for the best part of two decades.

From BBC ● Jul. 18, 2026

So we'll go flat out and let's see how it goes.

From BBC ● Apr. 30, 2026

“Everything that we’ve got running is going to be flat out for the rest of the year,” Fitterling said.

From The Wall Street Journal ● Apr. 5, 2026

As Ike came up the side, Fadi ran, flat out, back the way he’d come.

From "Shooting Kabul" by N. H. Senzai