An Excerpt From Roughing It by Mark Twain

"'By George, the thoroughbrace is broke!'

This startled me broad awake--as an undefined sense of calamity is always apt to do. I said to myself: 'Now a thoroughbrace is probably a part of a horse; and doubtless a vital part, too, from the dismay in the driver's voice. Leg, maybe--and yet, how could he break his leg waltzing along such a road as this? No, it can't be his leg. That is impossible, unless he was reaching for the driver. Now, what can be the thoroughbrace of a horse, I wonder? Well, whatever comes, I shall not air my ignorance in this crowd, anyway."