Longman Dictionary of Contemporary English
Wiktionary
a. 1 Having a sagged back. 2 Having sagged or hollow surface. 3 (context figuratively English) old#English.
WordNet
Usage examples of "swaybacked".
Abattoir He cruised through an outlying neighborhood of decrepit houses: ruptured sidewalks, swaybacked steps, broken porch railings, aged and weathered walls.
Paul, the stable master, had already prepared the swaybacked pack mare with the baggages she would be taking with her.
The silhouette creaks into the brown-boarded shape of a farm wagon pulled by a single large, if swaybacked, gray horse.
I stayed close to the house, and I pedaled Rocket around as gingerly as riding one of those swaybacked ponies that plods in circles at the county fair.
The girls would grow positively swaybacked with perkiness, and Maggie knew it was they who didn't stand a chance.
Then after cleaning the animals' stalls, picking the infectious dung and hay from the horse's hooves and treating the swaybacked pony for ringbone, they could have the rest of the day for playing.