noun

radioactivity

/ˌreɪdiəʊækˈtɪvɪti/ · say it: RAY·dee·oh·ak·TIV·uh·tee

the emission of radiation from unstable atomic nuclei

In more detail

1. (noun) the process by which certain substances send out energy in the form of rays or particles because their atoms are unstable

2. (noun) the energy or rays that are sent out by a radioactive substance

Examples

1. The radioactivity of uranium makes it dangerous to handle without protection.
2. The radioactivity in the contaminated area forced residents to evacuate.

How to use radioactivity

Radioactivity refers to the spontaneous emission of energy and particles from unstable atomic nuclei, or the phenomenon itself. It is used in scientific, medical, and environmental contexts to describe both the process and the resulting radiation. The term is more technical than the general word 'radiation' and specifically denotes atomic-level processes.

Common phrases

radioactivity levels
radioactive decay
background radioactivity
measure radioactivity
emit radioactivity

Synonyms

radiation · radioactive decay · nuclear radiation · atomic radiation

Word family

radioactive (adjective) · radioactively (adverb) · radioisotope (noun) · radionuclide (noun)

A common mistake

Learners sometimes confuse radioactivity with radiation, using them interchangeably; however, radioactivity is the source process while radiation is the energy emitted.

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