flat_out
1. [ adverb ] in a blunt direct manner
Synonyms: bluntly brusquely roundly bluffly
Examples:

"he spoke bluntly" "he stated his opinion flat-out" "he was criticized roundly"

Related terms: blunt brusque bluff blunt brusque
2. [ adverb ] at top speed
Synonyms: like_blue_murder
Examples:

"he ran flat out to catch the bus" "he was off down the road like blue murder"

3. [ adverb ] at top speed
Examples:

"ran flat out to catch the bus"

Similar spelling:   flood_out