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flat-out

adjective \ ˈflat-ˌau̇t \

Definition of flat-out

1 :being or going at maximum effort or speed
2 :out-and-out, downright
  • it was a flat-out lie

See flat-out defined for English-language learners

From the M-W Editors

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First Known Use of flat-out

1906

flat-out Synonyms

Synonyms
all-out, arrant, blank, blooming [chiefly British], bodacious [Southern & Midland], categorical (also categoric), clean, complete, consummate, cotton-picking, crashing, damn, damned, dead, deadly, definite, downright, dreadful, fair, flat, flat-out, out-and-out, outright, perfect, plumb, profound, pure, rank, regular, sheer, simple, stark, stone, straight-out, thorough, thoroughgoing, total, unadulterated, unalloyed, unconditional, unmitigated, unqualified, utter, very
Related Words
authentic, classic, genuine, real, veritable; constant, endless, eternal, perpetual, undying, unremitting; extreme, unrestricted; confirmed, habitual, hopeless, inveterate; extraordinary, frightful, horrible, huge, main, superlative, supreme, surpassing, terrible, terrific
Near Antonyms
doubtful, dubious, equivocal, qualified, questionable, restricted, uncertain

flat out

adverb

Definition of flat out

1 :in a blunt and direct manner :openly
  • called flat out for revolution
  • —Nat'l Review
2 :at top speed or peak performance
  • the car does 180 m.p.h. flat out
3 usually flat-out play \ˈflat-ˌau̇t\ :absolutely, downright —usually used as an intensive
  • is just flat-out confusing

See flat out defined for English-language learners

Examples of flat out in a Sentence

  1. I told him flat out that I have no intention of marrying him.

  2. We asked for more time but they refused us flat out.

  3. The car does 180 mph flat out.

First Known Use of flat out

1932

FLAT-OUT Defined for English Language Learners

flat-out

adjective

Definition of flat-out for English Language Learners

  • : absolute and complete

  • : greatest possible

flat out

adverb

Definition of flat out for English Language Learners

  • : in a very clear and direct way

  • : at the fastest possible speed

  • —used to make a statement more forceful

FLAT-OUT Defined for Kids

flat-out

adjective \ ˈflat-ˌau̇t \

Definition of flat-out for Students

1 :2out-right 1
  • That's a flat-out lie.
  • —Phyllis Reynolds Naylor, Shiloh
2 :greatest possible
  • a flat-out effort

flat out

adverb

Definition of flat out for Students

1 :in a very clear manner
  • I told him flat out to leave.
2 :at top speed
  • We worked flat out to finish.

Learn More about flat-out

  1. See words that rhyme with flat-out Thesaurus: All synonyms and antonyms for flat-out

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Examples: flat-out in a Sentence