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# radioactivity

noun (radioactivity, uncountable)

«radioactivity» in the English dictionary: everyday — its meanings, how the lessons use it, and examples, each with its tree on Mova.

## Everyday

1. Radioactivity is the giving off of invisible energy, called radiation, by the centres (nuclei) of some unstable atoms as they break down. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#m1)
2. Radioactivity is also a measure of how much of this radiation something gives off. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#m2)

### In the lessons

In science lessons it is introduced with Marie Curie, who studied it and won two Nobel Prizes, with uranium and radium, nuclear power stations, X-rays and safety signs (the yellow trefoil). In everyday life small amounts of radioactivity are all around us naturally, even in bananas and rocks; large amounts are dangerous. Phrases: «levels of radioactivity», «measure radioactivity», «natural radioactivity».

### Examples

- Marie Curie studied radioactivity and discovered radium and polonium. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x1)
- A Geiger counter clicks when it detects radioactivity. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x2)
- High levels of radioactivity can damage living cells. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x3)
- Bananas have a tiny, harmless amount of radioactivity. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x4)
- After the Chernobyl accident, radioactivity spread over a wide area. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x5)
- Scientists use radioactivity to date very old objects. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x6)
- The yellow warning sign means radioactivity is present. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#x7)

### Note

Uncountable. Adjective: radioactive. Radioactivity is not the same as radio waves; radios use a harmless kind of wave. Myth: radioactive things do not glow green like in cartoons.

## On Mova

- [Trees and pragmatics of «radioactivity» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/): every meaning and example parsed by Mova, with its dependency tree and frames.
- [«radioactivity» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/radioactivity.html) on Mova free.