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

His accusation, Jones told Salon, is flat-out false.

From Salon • Mar. 11, 2026

At that awards show, when former Times columnist Amy Kaufman — then recently engaged herself — asked the “Dune” actor flat-out if she was engaged, Zendaya flashed her ring, smiled coyly and shrugged her shoulders.

From Los Angeles Times • Mar. 2, 2026

So Sauer’s claim that Murphy forced an unscheduled emergency stopover in Djibouti is just flat-out false.

From Slate • Feb. 28, 2026

A 2016 consumer alert from the Federal Trade Commission, which appears to be the latest on the topic, warned people against this option, saying that the deals can be risky or “even flat-out scams.”

From MarketWatch • Feb. 4, 2026

I hate to admit it, but we flat-out lied, shaking our heads vigorously from left to right.

From "Courage to Soar" by Simone Biles