Green’s Dictionary of Slang

a hunchback.

1654		Mercurius Fumigosus 3 14-21 June 4: She was Beetle-brow'd, Monkey-proud, Leathern-Ear'd, Hawkes-nos'd, Wry-mouth'd, Crump-backt, Hopper-arst, Splay-footed.
1672		Topsie-turvy, hey-down-derry 14: Bald, Nasty, Crumps, Toothless, [...] yet so delighted with Life, that to be thought Young, one dies his Gray Hairs, another covers his Baldness with a Periwig.
1711		‘The Fart’ in Farmer Merry Songs and Ballads (1897) III 184: She the Sisters had met, / Bowing low with her back-bone crump, / As she gave a Salute.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.