Green’s Dictionary of Slang

the southwestern counties of England: Somerset, Devon, Cornwall, Dorset.

c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Zed-land, Somersetshire, Devbonshire & Devonshire where the letter S is pronounced Z.
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn).
1811		Lex. Balatronicum.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
1890–1904		Farmer & Henley Sl. and Its Analogues.