👉 Undergroundness is a concept in physics and engineering that describes how an object's surface behaves under pressure. It is named after the underground space, which is where objects are found underground or beneath the surface of the Earth. In everyday language, "undergroundness" refers to an object's sensitivity to changes in pressure. For example, if you were to apply a force to an object that is located below the ground, and then stop applying the force, the object would return to its original position