E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Respectability. A word invented by Carlyle. A witness in the trial of John Thurtell said, I always thought him [Thurtell] a respectable man. And being asked by the judge what he meant, replied, He [Thurtell] kept a gig.
A princess of the blood, yet whose father had sold his inexpressibles in a word, Gigmanity disgigged. Carlyle: The Diamond Necklace, chap. v.