ground-zero

Noun

ground zero (countable and uncountable, plural ground zeroes)

1. Originally, the point on the land or water surface below which a nuclear bomb detonates in the air; now also the point on such a surface at or above the detonation.
   • Some of the construction details (reinforcing rod splices, for example) [in Hiroshima and Nagasaki, Japan] were often poor, and much of the concrete was definitely weak; thus some reinforced concrete buildings collapsed and suffered structural damage when within 2,000 feet of ground zero, and some...1946 June 19, U.S. Strategic Bombing Survey, “The Effects of the Atomic Bombings”, in The Effects of the Atomic Bombings of Hiroshima and Nagasaki, [s.l.]: Chairman’s Office, →OCLC, archived from the...
2. (broadly) The location of any disaster or violent assault.
   • "This is ground zero," she said. "If regulators don't adopt a zero tolerance for violations of standards then what we will have are places that are going to have unacceptable environmental damage."2011 April 21, Suzanne Goldenberg, quoting Jan Jarrett, “Pennsylvania: the ‘ground zero’ of the US shale gas drilling boom”, in The Guardian
3. (figuratively) The point at which something begins.
   • James Meredith's forced admission was a milestone in upending the old order in America's most segregated state, a kind of race relations ground zero.1997 May 4, Adam Nossiter, “Ground Zero”, in The New York Times, →ISSN

See all 4 meanings of ground zero