idiom · a sudden failure or setback caused by a miscalculation or a lapse in attention

没想到他这样精明的人也会马失前蹄，在那笔生意上亏了本。

expression · the literal occurrence of a horse losing its footing with its front legs

战马在冲锋时突然马失前蹄，把背上的士兵摔了下来。