flat out

Short definition from Wiktionary

Adjective

1. 1
   Used other than figuratively or idiomatically: see flat, out.
2. 2
   Complete, total, downright.
3. 3
   Very busy.
4. 4
   Lazy, sleeping.
5. 5
   Alternative form of flat out.

Adverb

1. 1
   At top speed.
2. 2
   Without hesitation or reservation, bluntly, no holds barred, totally, outright.
3. 3
   Alternative form of flat out.

Noun

1. 1
   A total failure.
2. 2
   A baked portion of flatbread; a baked item that is not meant to rise.
3. 3
   A wrap, an item of food consisting of various ingredients wrapped in a tortilla or pancake.
4. 4
   A section of piste that is relatively flat, causing or allowing skiers to slow down.
5. 5
   An uncambered corner of racetrack; a racetrack whose corners are uncambered.

Verb

1. 1
   To fail after a promising beginning; to disappoint expectations.
2. 2
   Synonym of flatten out (to make flat)