1926, from German Zyklon, commercial name of a type of hydrogen cyanide, of unknown etymology, but it is the usual German form of the word cyclone. Originally used as a pesticide and fumigant.
Examples from the Web for zyklon
Zyklon B, a gas used by the Nazis in the death camps, is a haunting example of the rapid lethality of one form, hydrogen cyanide.Sarin, Nitrogen Mustard, Cyanide & More: All About Chemical Weapons|Kent Sepkowitz|August 26, 2013|DAILY BEAST
In the next case are photocopies of transit passes for the trucks that brought the cannisters of Zyklon B pellets.
Finally the empty canisters of Zyklon B, perhaps a hundred or more, in a pile.