Wiktionary
n. The back of a mule.
Usage examples of "muleback".
Although the grueling trip on muleback to Vera Cruz had almost finished him off, he was recovering now.
She kept on thinking about him during the arduous muleback crossing of the hallucinating plateau where Aureliano Segundo had become lost when he was looking for the most beautiful woman who had ever appeared on the face of the earth, and when they went over the mountains along Indian trails and entered the gloomy city in whose stone alleys the funereal bronze bells of thirty-two churches tolled.
Foster's six little field guns, which had accompanied his lightning operations on muleback, did yeoman service that day, wreaking gory lanes through the compressed mass of horse- and man-flesh until, when he felt the time was ripe, he ordered in de Burgh and Viscount Sir Henry Powys, commanding the Royal Tara Gallowglasses and the Cumberland Heavy Dragoons, respectively.