Moving recklessly fast, with determination
This phrase dates from the 1800s and refers to riding horseback. Leather alludes to a horse’s saddle and the leather crop used to encourage the horse. It’s a colloquial expression originating in America, but may have sprung from the earlier British army jargon ‘hell for leather,’ first recorded in 1889.
The unusual thing about “hell bent for leather” is that it appears to be a combination of two phrases: “hell bent” and “hell for leather,” which also date to the late 19th century. “Hell for leather” specifically means riding a horse very fast. Rudyard Kipling used the phrase: (“Here, Gaddy, take the note to Bingle and ride hell-for-leather,” Story of the Gadsbys, 1889), and probably contributed to its popularity.
“Hell bent for leather” doesn’t exactly make any more literal sense than “hell for leather,” but the fact that “hell bent” is more widely understood may have led to the fusion of the two phrases. A dictionary meaning of the word “for” is “because of” or “the result of,” so, “hell bent for leather” means going somewhere as quickly as possible because you’re whipping the horse to get there faster.
“Bent” means a direct route, or directed on a course. So, “hell bent” would suggest going somewhere in a very determined manner. “Hell” is not meant to be the destination; it merely strengthens, or intensifies, the rest of the phrase. For example, “What the hell are you doing?” doesn’t really have anything to do with Hell. It merely indicates you want your question answered ‘or else.’
There are a number of variants: “hell-bent for election,” “hell-bent for breakfast,” “hell-bent for Sunday,” and “hell-bent for Georgia.” “Hell-bent for breakfast” is my personal choice, of course, since it’s the only that has anything to do with food.
We don’t know whether the original sense was “willing to go to hell to achieve one’s goal,” or just “really, really determined,” but it seems best not to interfere with someone “hell bent” on anything.
The phrase is also the title of a 1960s Western movie. With the allusions to horses, saddles, whips, and hell, it would have to an oater, right?