E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
An evasion. In French pleadings each separate allegation in the plaintiffs charge, and every distinct plea in the defendants answer used to begin with quil est; whence our quillet, to signify a false charge, or an evasive answer.
Oh, some authority how to proceed;
Some tricks, some quillets, how to cheat the devil.