gun·pow·der (gŭn'pou'dər) n. Any of various explosive powders used to propel projectiles from guns, especially a black mixture of potassium nitrate, charcoal, and sulfur.
1411, from gun + powder. The Gunpowder Plot was the conspiracy to blow up the Houses of Parliament on Nov. 5, 1605, while the King, Lords and Commons were assembled there.