A-bomb, atom bomb, atomic bomb, fission bomb, plutonium bomb - a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)

atomic warhead, nuclear warhead, nuke, thermonuclear warhead - the warhead of a missile designed to deliver an atom bomb

fusion bomb, H-bomb, hydrogen bomb, thermonuclear bomb - a nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium

megaton bomb - a nuclear weapon with an explosive power equivalent to one million tons of TNT

W.M.D., weapon of mass destruction, WMD - a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)