radioactive decay

American  

[rey-dee-oh-ak-tiv di-key] / ˌreɪ di oʊˈæk tɪv dɪˈkeɪ /

noun

Physics.

1. a radioactive process in which a nucleus undergoes spontaneous transformation into one or more different nuclei and simultaneously emits radiation, loses electrons, or undergoes fission.

---

radioactive decay British  

noun

1. Sometimes shortened to: decay.  Also called: disintegration.  disintegration of a nucleus that occurs spontaneously or as a result of electron capture. One or more different nuclei are formed and usually particles and gamma rays are emitted

---

radioactive decay Scientific  

/ rā′dē-ō-ăk′tĭv /

1. The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles. The rate of decay of radioactive substances such as carbon 14 or uranium is measured in terms of their half-life.

2. See also decay radioisotope

---

Etymology

Origin of radioactive decay

First recorded in 1960–65

Example Sentences

The nonrenewable gas is produced by radioactive decay deep under the earth and escapes into space once released.

From The Wall Street Journal • Mar. 31, 2026

One of the best known is radioactive decay: a process where due to quantum effects, elementary particles can escape the attractive force that ties them to atomic nuclei.

From Science Daily • Apr. 26, 2024

Helium is a byproduct of natural gas extraction, and it also occurs naturally from radioactive decay in the Earth’s crust.

From Seattle Times • Feb. 2, 2024

The breakthrough came when a method, which measures radioactive decay, dated the fossils to 564 million years ago, plus or minus 700,000 years.

From BBC • Jan. 21, 2024

Instead, Voyager relies on a small nuclear power plant, drawing hundreds of watts from the radioactive decay of a pellet of plutonium.

From "Cosmos" by Carl Sagan