nuclear

The word “nuclear” means relating to the nucleus of an atom, or to energy released by splitting or joining atomic nuclei. In plain terms, relating to the core of an atom, atomic energy, or atomic weapons.

“Nuclear” is pronounced NYOO-kleer (/ˈn(j)u.kli.ɚ/ in IPA).

Here is “nuclear” used in a sentence: “The country relies heavily on nuclear power for its electricity.”

“Nuclear” is an adjective.

The word “nuclear” comes from Latin. From "nucleus" + "-ar," ultimately from Latin nucleus, "kernel" — the tiny dense core at the centre of an atom.

“Nuclear” is a very common word in modern English, usually learned at around the B1 level.

“Nuclear” has 2 distinct senses listed in this dictionary. The most common is: relating to the nucleus of an atom, or to energy released by splitting or joining atomic nuclei.

Both release nuclear energy but in opposite ways. Fission splits a heavy atomic nucleus, such as uranium, into smaller pieces — the process used in today's power stations. Fusion joins light nuclei, such as hydrogen, into heavier ones, releasing even more energy. Fusion is how the Sun shines, and scientists are still working to harness it on Earth.

Its best-known use is generating electricity, where heat from splitting atoms boils water to drive steam turbines. The same principles power some submarines and ships, and produce medical isotopes used in scans and cancer treatment. The technology also underlies nuclear weapons, which is why it is so tightly regulated worldwide.

It depends on how you weigh the trade-offs. Nuclear power generates large amounts of low-carbon electricity without burning fossil fuels, a real advantage for the climate. The drawbacks are radioactive waste, high building costs, and the risk of serious accidents. Most experts treat it as one useful option among many, rather than simply good or bad.