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# radioactivity

«radioactivity» in Mova's school dictionary: **the giving off of invisible energy, called radiation, by…** — its meaning for a pupil, its sense in the lessons and examples.

### part of speech

noun (radioactivity, uncountable)

### meaning for a pupil

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://md.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://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/#m2)

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

### Trees and pragmatics

[Every meaning and example of «radioactivity» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/R/radioactivity/), each sentence with its dependency tree and frames.