- (pron. nook-yoo-ler)
Usually applied to something that either involves fusion (joining atomic nuclei) or fission (splitting atomic nuclei).
Both of these liberate large amounts of energy and can thus be used in atomic weapons. The classic atom or A bomb is a fission weapon, whereas the generally more powerful hydrogen or H bomb is a fusion weapon.
Also used as a descriptor for power stations that run an atomic reactor as their heat source. Currently, these are all fission types but work continues to develop a fusion reactor. The latter has the great advantage of only needing deuterium (an isotope of hydrogen) as its fuel and producing helium (an inert gas, wouldn't ert a fly) instead of the fission reactor which needs uranium or plutonium as a fuel and produces a whole host of unpleasant highly radioactive waste products.
That said, a little mutation from time to time is good for the species. There may be good reasons to have two heads, but only time and Darwin will tell.