Camouflet
A camouflet, in military science, is an artificial cavern created by an explosion. If the explosion reaches the surface then it is called a crater.[1]
The term originated in a countermine dug by defenders to defend against the undermining of a fortress's walls during a siege. The defenders would dig a tunnel under the attackers' tunnel. An explosive charge would be set off to create a camouflet that would collapse the attackers' tunnel.[2]
More recently, the term has been used to describe the effects of very large bombs like the Grand Slam bomb, which are designed to penetrate next to a large target structure and create a camouflet to undermine the foundations of the structure. It has been observed that it is more efficient to penetrate ground next to the target than on target.
