nuclear test ban treaty

noun

1. an agreement signed by Britain, the Soviet Union, and the U.S. in 1963, committing nations to halt atmospheric tests of nuclear weapons: by the end of 1963, 96 additional nations had signed the treaty.

An agreement made in 1963 by Britain, the Soviet Union, and the United States not to test nuclear weapons in the air, in outer space, or under the sea. Underground testing was permitted under the treaty.