View synonyms for radioactive


[ rey-dee-oh-ak-tiv ]


  1. Physics, Chemistry. of, relating to, exhibiting, or caused by radioactivity:

    A pressing issue in post-Soviet Russia is safe long-term storage of radioactive waste, from both military and civilian applications.

  2. relating to or being a person, topic, or matter that is likely to provoke intense negative reactions or disagreement:

    The option of raising taxes to fund these expenditures is a politically radioactive approach that a majority of state policymakers have avoided.


/ ˌreɪdɪəʊˈæktɪv /


  1. exhibiting, using, or concerned with radioactivity


  1. A descriptive term for a material made up of atoms in which radioactivity occurs.

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Derived Forms

  • ˌradioˈactively, adverb

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Other Words From

  • ra·di·o·ac·tive·ly adverb
  • non·ra·di·o·ac·tive adjective
  • un·ra·di·o·ac·tive adjective

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Word History and Origins

Origin of radioactive1

First recorded in 1895–1900; radio- + active

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Example Sentences

Thorium and uranium, which could be used for radioactive fuel, are found together in 34 regions that are areas of less than 80km wide.

Members of the Borexino collaboration in Italy started by developing the technology to purge the materials from which they would build their detector of polluting radioactive ingredients.

Yet when it comes to helping Guam veterans who have been historically exposed to toxic chemicals such as Agent Orange and radioactive materials, Veterans Affairs provides little to no help to these residents.

From Vox

Everyone knows Peter Parker, the guy from Queens who was bitten by a radioactive spider and became Spider-Man.

Wudan Yan looks at new attempts to tackle the problem of storing nuclear waste, some of which will stay radioactive for millions of years.

He was radioactive to those who once valued his political counsel and editorial avidity.

He was struck down inside an upmarket London hotel by a rare radioactive poison that had been slipped in to his pot of tea.

The Japanese monster gets a $160 million blockbuster reboot and protects mankind against a pair of radioactive MUTOs.

That would be Nobel Prize winner Marie Curie, the gal who discovered radioactive polonium.

The Iranians now have most of the know-how and most of the radioactive stuff they need to build a bomb.

He thinks the big comet which hit the earth contained radioactive gas that made us all into metal.

A radioactive sodium atom contains a different number of neutrons.

Fortunately each kind of radioactive atom decays with a unique “pattern” scientists call a 11 “decay scheme”.

To do this we have to know the types of radiation emitted by the radioactive atoms we are trying to measure.

Radioactive atoms almost always decay by emitting negatively charged beta particles usually accompanied by gamma rays.


Related Words

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More About Radioactive

What does radioactive mean?

Radioactive describes something that exhibits or is caused by radioactivity. If something is radioactive, it emits radiation, which usually takes the form of electromagnetic waves or fast-moving elementary particles, such as protons or neutrons.

While low doses of radiation are usually harmless, being exposed to large amounts of radiation will most likely kill you. For this reason, highly radioactive materials are often considered very dangerous and will only be handled by experts.

Example: The radioactive waste produced by nuclear power plants can damage the environment. 

Where does radioactive come from?

Radioactive was first recorded around 1895. It combines radio-, which refers to energy transmitted in wave motion (radiant energy), and active, which describes something being in action or motion. If something is radioactive, it is releasing energy that is usually moving very fast.

What makes something radioactive? In chemistry, everything is made up of atoms, and that atom has a nucleus containing protons and neutrons. The nucleus wants the same number of electrons and neutrons. If they aren’t the same, the nucleus will remove electrons or neutrons until there is an equal number within the nucleus. The released protons and neutrons are called radiation, and an element that releases radiation is radioactive.

Radioactive materials can be dangerous because the radiation can damage a living thing’s DNA (which is really bad) or cause mutations in living cells (which is also really bad).

While the effects will be different depending on the specifics of the radioactive material, one of the most common negative effects is cancer, which is caused by mutating cells. For this reason, governments usually will not allow people (or businesses) to own or handle dangerous radioactive materials without a license.

Because of these laws, unless you work in a nuclear power plant or are a nuclear chemist, you most likely won’t have to worry about whether something is radioactive.

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What are some other forms related to radioactive?

  • radioactivity (noun)
  • radioactively (adverb)
  • nonradioactive (adjective)
  • unradioactive (adjective)

What are some words that share a root or word element with radioactive

What are some words that often get used in discussing radioactive?

How is radioactive used in real life?

In everyday life, radioactive is generally used only by scientists and people interested in nuclear science or in related news stories. However, radioactive materials sometimes appear in fiction and pop culture.

Try using radioactive!

True or False?

If something is radioactive, it is stable and will not release any radiation.




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