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Glite Dictionary
🗣️ Directly or bluntly 🏃 At full speed
flat out

flat out

4 4.3
To do something as fast and as hard as possible
  • idiom
  • /flæt aʊt/
  • Informal
translation icon : a tope (informal)
  • I've got in the bus lane flat out down towards the lights.
  • ran flat out
  • worked flat out
  • go flat out

I've got in the bus lane flat out down towards the lights.

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Examples

  • It was really fun going flat out over the dry lake beds.

    Blog text (18)

  • I've been away for a while running flat out at work... but... games!

    Blog text (15)

  • Going flat out, the BE2 could not manage much above 70 mph.

    Fiction book (1994)

  • All oil producers are producing flat out, with the possible exception of the Saudis.

    Blog text (19)

  • I don't drink coffee or tea, and food doesn't do it for me, so I go into the office, start at 7, and work flat out until 12 (taking a couple of minute breaks every hour).

    Blog text (7)

  • Thus, nuclear plants make for great baseload power—they are run flat out because their marginal costs are so low.

    Blog text (25)

  • If you were fortunate enough to witness Verlander's stretch of flat-out dominant pitching in the summer of 2011, you probably feel he wasn't up to that level in 2012.

    Blog text (2)

  • The team is working flat out to meet the deadline for the important project.

  • He ran flat out to catch the bus before it left the station.

  • During the tournament, the players trained flat out to prepare for the championship.

Synonyms

like hell
vsflat out
  • NSFW
75 7.9

Happening very quickly, with great effort or very strongly

is similar but can be used more neutrally across contexts
all-out
vsflat out
68 4.1

Very determined and using all available effort

focuses more on extreme effort than only quickness or speed
full throttle
vsflat out
12 5.8

A state of moving at the highest speed and with the most effort

is the same idea expressed as top speed or maximum effort
balls to the wall
vsflat out
  • Offensive
2 9.4

Do something with as much speed and effort as possible, without holding back

matches intensity but is more neutral in tone and use
balls-out
vsflat out
  • Offensive
1 9.9

Very bold and energetic without caring about risk

shares high intensity but stresses speed and steady effort more
in nothing flat
vsflat out
  • Archaic
1 7.0

In a very short time

focuses on immediate quickness rather than prolonged maximum effort
nothing flat
vsflat out
  • Informal
1 8.5

Very quickly without delay

emphasizes speed alone rather than sustained top effort
at full tilt
vsflat out
  • Informal
1 5.6

With as much speed and effort as possible

is the general phrase for top speed or maximum effort
like blue murder
vsflat out
  • UK
9.9

Acts very quickly and with great force

is similar but may be less idiomatic in everyday speech

Antonyms

slowly
∞ 1.0

At a low speed without hurrying

leisurely
30 3.4

In a relaxed way without hurrying

How Fast

flat out
  • Informal
4 4.3
fast
∞ 1.0
slowly
∞ 1.0

Surface Forms

flat out positive

Morphology

flat + out

The sense 'as fast/as hard as possible' is partially derivable because 'flat' can function as an intensifier meaning 'completely' and 'out' adds emphatic extension, so there is a visible compositional link to extreme degree. However, the particular combination is conventionalized and not a straightforward spatial or literal composition, so a B1 learner who only knows basic senses of 'flat' (level/plain) and 'out' (away) may not reliably infer the idiomatic intensive meaning.

Etymology

Flat out may come from the image of pressing the car's gas pedal flat to the floor so the engine runs at full power. So it means 'at maximum speed' or 'with all your effort'.