moving or working at top speed or with maximum effort; all-out.
a flat-out effort by all contestants.
downright; thoroughgoing.
Many of the paintings were flat-out forgeries.
In a direct manner, bluntly. For example, He told the true story flat out . [ Colloquial ; mid-1900s]
At top speed, as in She was running flat out to catch the train . [ Slang ; c. 1930]
First recorded in 1925–30
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
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
Romero explains how the Supreme Court is essentially treating Callais “as a stand-in for principles that the justices either did not discuss in that case or flat-out claimed to reject.”
From Slate • 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
Horan was flat-out glad to be alive, and relieved to be back in the safety and relative comfort of the Marine Corps.
From "Boots on the Ground: America's War in Vietnam" by Elizabeth Partridge
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
