flat-out

[flat-out]

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.

Word History and Origins

Origin of flat out¹

First recorded in 1925–30

Idioms and Phrases

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]