Definition of the word ground zero

The term "ground zero" originated during World War II to describe the point directly above or below the epicenter of an atomic bomb explosion. The term "zero" refers to the radius where structures would be destroyed completely, hence the name "ground zero" for the location on the surface where such destruction occurred. The term gained widespread usage during the aftermath of the terrorist attacks on the World Trade Center in New York City on September 11, 2001, when the destroyed site of the Twin Towers was called "ground zero." Today, the phrase "ground zero" is commonly used to refer to the locations of any major disasters or catastrophic events, such as hurricanes, earthquakes, and explosions.