confederacy, conspiracy - a group of conspirators banded together to achieve some harmful or illegal purpose

criminal, crook, felon, malefactor, outlaw - someone who has committed (or been legally convicted of) a crime

Fawkes, Guy Fawkes - English conspirator who was executed for his role in a plot to blow up James I and the Houses of Parliament (1570-1606)

Oates, Titus Oates - English conspirator who claimed that there was a Jesuit plot to assassinate Charles II (1649-1705)