nuclear weapon

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A weapon, such as an atomic bomb or hydrogen bomb, whose destructive power comes from the release of nuclear energy.

from the GNU version of the Collaborative International Dictionary of English.

• noun A weapon of great explosive power, such as an atomic bomb or a hydrogen bomb, which depends for most of its explosive power on the release of energy from within atomic nuclei by a nuclear reaction. A fission weapon or a fusion weapon. The term includes atomic shells for cannon.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A weapon that derives its energy from the nuclear reactions of either fission or fusion.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a weapon of mass destruction whose explosive power derives from a nuclear reaction