A jeering appellation given to any person who limps, or is lame; St. Giles was the patron of cripples, lepers, &c. Churches dedicated to that saint commonly stand out of town, many of them having been chapels to hospitals. See Gyles.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Hopkins * Hopper-arsedNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes