Delay-action bomb
（重定向自Delayed action fuse）
A delay-action bomb is an aerial bomb designed to explode some time after impact, with the bomb's fuzes set to delay the explosion for times ranging from very brief to several weeks. Short delays were used to allow the bomb to penetrate before exploding: "a delay action bomb striking the roof of a tall building will penetrate through several floors before bursting"; longer delays were intended to disrupt salvage and other activities, and spread terror, in areas where there could still be live bombs, and to attack bomb disposal workers.