Noun
a storehouse (as a compartment on a warship) where weapons and ammunition are stored
Source: WordNetA powder magazine was hacked out of the bedrock beneath the Joannes bastion. Source: Internet
It blew up as a result of heated cannon shot from a gunboat hitting the powder magazine, killing all its inhabitants. Source: Internet
In the afternoon of 18 November 1857, a huge explosion rocked Mainz when the city's powder magazine, the Pulverturm, exploded. Source: Internet