nu·cle·ar 
(nklē-ər, ny-)
(nklē-ər, ny-)adj.
1. Biology Of, relating to, or forming a nucleus of a cell: a nuclear membrane.
2. Physics
a. Of or relating to atomic nuclei: a nuclear chain reaction.
b. Using or derived from the energy of atomic nuclei: nuclear power.
3. Of, using, or possessing atomic or hydrogen bombs: nuclear war; nuclear nations.
4. Drastic or extreme; radical: "The Senate majority leader ... had vowed to invoke what some have called the nuclear option to do away with judicial filibusters" (Carl Hulse).
[From NUCLEUS.]
Usage Note: The pronunciation (nkyə-lər), which is generally considered incorrect, is an example of how a familiar phonological pattern can influence an unfamiliar one. The usual pronunciation of the final two syllables of this word is (-klē-ər), but this sequence of sounds is rare in English. Much more common is the similar sequence (-kyə-lər), which occurs in words like particular, circular, spectacular, and in many scientific words like molecular, ocular, and vascular. Adjusted to fit into this familiar pattern, the (-kyə-lər) pronunciation is often heard in high places. It is not uncommon in the military in association with nuclear weaponry, and it has been observed in the speech of US presidents, including Dwight D. Eisenhower and George W. Bush. The prominence of these speakers, however, has done little to brighten the appeal of (nkyə-lər), which was considered acceptable to only 10 percent of the Usage Panel in our 2004 survey.