idioms using “flat”

Flat-out

Completely or totally (used as an intensifier)

“This instruction booklet is just flat-out confusing.”

Flat out

At top speed or performance

“The translators are working flat out to finish the transcript by the deadline.”

Flat-footed

Clumsy, unimaginative

“His first attempt at writing his autobiography was rather flat-footed and dull.”

Flat

Completely

“We were flat broke as students but managed to have a lot of fun anyway.”

Fall flat

To fail to impress

“The company’s stock tumbled 10% in one day after the CEO’s speech fell flat with the company’s investors.”