WordNet (r) 3.0 (2006):

A-bomb
    n 1: 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) [syn: atom bomb,
         atomic bomb, A-bomb, fission bomb, plutonium bomb]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "A-bomb":
   H-bomb, atomic bomb, atomic warhead, clean bomb, cobalt bomb,
   dirty bomb, fusion bomb, hell bomb, hydrogen bomb,
   limited nuclear weapons, nuclear artillery, nuclear explosive,
   nuclear warhead, plutonium bomb, superbomb,
   tactical nuclear weapons, thermonuclear bomb,
   thermonuclear warhead