hog-backed
/ˈhɒɡbakt/(also hog's-backed)
adjective
1Of an animal or person: having an arched or rounded back.
2Of a thing: having a rise in the middle.
Origin
Early 17th century; earliest use found in John Speed (d. 1629), historian and cartographer. Partly from hog + backed, and partly from hogback + -ed.