nu·cle·ar (nklē-ər, ny-)
1. Biology Of, relating to, or forming a nucleus of a cell: a nuclear membrane.
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).
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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.