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1. clearly and definitely; holding nothing back. I told her flat out that I didn't like her. They reported flat out that the operation was a failure.
2. at top speed. How fast will this car go flat out? This car will hit about 110 miles per hour flat out.
1. clearly and without confusion The coach told me flat out, “You're too small.” I don't want to flat out say I never did it when maybe I just don't remember having done it.
2. as fast as possible The painters have been working flat out to get the job finished. She drives as though her car has only two speeds – flat out and stopped.
1. if a person or a machine is doing something flat out, they are doing it as fast and with as much energy as they can (often + to do sth) The decorators have been working flat out to get the job finished. My car only does 60 mph, even when it's going flat out.
2. (American) if someone says something flat out, they say it in a very clear and direct way, even if it might upset people He called up and flat out asked if I was having an affair with Bob.See fall flat
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]
1. mod. totally. We were all flat out disgusted.
2. mod. at top speed. If we run flat out, we can get there before dusk.