Gunpowder plot has 2 different meanings across 2 categories:
a conspiracy in 1605 in England to blow up James I and the Houses of Parliament to avenge the persecution of Catholics in England; led by Guy Fawkes
A failed plot, in November 1605, to kill the Protestant king James I of England and VI of Scotland, and to blow up the House of Lords using gunpowder, annually commemorated on Guy Fawkes Day.