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Definition of radioactivity

radioactivity

/ˌreɪdioʊækˈtɪvɪti/
ra · di · o · ac · tiv · i · ty
Adverb:radioactively
•
Plural:radioactivities
•
Adjective:radioactive
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radioactivity Lexical Profile

radioactivity Game Scores & Validity

• noun

1

The spontaneous emission of ionizing radiation or subatomic particles caused by the disintegration of unstable atomic nuclei.

Example

"Henri Becquerel discovered natural radioactivity while studying the properties of uranium salts."

2

Particles or rays emitted by the nuclear decay of radioactive substances, or the presence of such hazardous emissions in an environment.

Example

"Inspectors used Geiger counters to measure the level of radioactivity in the soil around the decommissioned power plant."

Synonyms
View all synonyms for radioactivity

Word Nuance & Usage

'Radioactivity' refers to the physical process of atomic nuclei decaying, or to the property of a substance that undergoes this decay, whereas 'radiation' refers to the actual energy or particles emitted during the process.

• Rhymes for radioactivity

• Nearby Words

radio
radioactive
radioactively
radioactivity
radiobroadcaster
radiogram
radiographer

Word Origin & Etymology

Coined in French as 'radio-activité' by physicists Marie and Pierre Curie in 1898, combining the Latin 'radius' (meaning 'ray' or 'beam') with 'activité' (meaning 'activity').

Cite this Entry

Wordmom. (2026). Definition of Radioactivity. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/radioactivity
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