E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Ethnic Plot.
The Popish plot. In Drydens satire of Absalom and Achitophel, Charles II. is called David, the royalists are called the Jews, and the Papists Gentiles or Ethnoi, whence Ethnic plot means the Gentile or Popish plot.