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Phrase(s): hell-bent for leather
Inf.moving or behaving recklessly; riding a horse fast and recklessly. • They took off after the horse thief, riding hell-bent for leather. • Here comes the boss. She’s not just angry; she’s hell-bent for leather.
McGrawhill's American Idioms And Phrasal Verbs
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Moving recklessly fast, as in Out the door she went, hell-bent for leather. The use of hell-bent in the sense of "recklessly determined" dates from the first half of the 1800s. Leather alludes to a horse's saddle and to riding on horseback; this colloquial expression may be an American version of the earlier British army jargon hell for leather, first recorded in 1889.
American Heritage Idioms