What does curie mean?
A curie is a non-SI unit used to measure radioactivity, defined as the quantity of any radioactive substance undergoing 3.7 × 10¹⁰ nuclear disintegrations per second. It was originally established as the approximate activity of one gram of pure radium and was named in honour of the French physicist Pierre Curie, a pioneer of radioactivity research. Although the International System of Units has replaced it with the becquerel — where one curie equals 3.7 × 10¹⁰ becquerels — the curie survives in older scientific literature, some regulatory documents, and fields like radiography and nuclear medicine, especially in the United States. It combines freely with metric prefixes, giving familiar forms such as millicurie, microcurie, and kilocurie. For readers encountering historical accounts of atomic science or radiation safety standards, knowing what a curie represents provides an essential link between early twentieth-century research on radium and modern measurements of radioactive decay.
nounA former unit of radioactivity, equal to the amount of a radioactive substance that undergoes 3.7 × 10¹⁰ disintegrations per second; it has largely been superseded by the becquerel in scientific use.
- A unit of radioactivity equal to 3.7 × 10¹⁰ nuclear disintegrations per second, originally based on the activity of one gram of radium.
"The laboratory sample measured several hundred millicuries of activity."
"The sealed vial contained roughly half a curie of radium-226."
"Regulations now express such quantities in becquerels rather than curies."
Regular plural formed by adding -es; used when specifying quantities of multiple units.
"The shipment was cleared only after inspectors confirmed it held fewer than ten curies of material."
The unit of radioactivity was named after a scientist who died from radiation exposure he didn't fully understand.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of curie
The curie takes its name from Pierre Curie (1859–1906), the French physicist who, alongside his wife Marie Skłodowska-Curie, conducted foundational research into radioactivity. The unit was adopted internationally in 1910 by the International Commission on Radiological Units, honouring his contribution to the field. It belongs to a family of eponymous scientific units, much as the becquerel honours Henri Becquerel, whose work the Curies built upon.
Related word forms
How curie is actually used
The curie is a non-SI unit that remains in occasional use, particularly in older literature and certain regulatory contexts, but has been officially replaced by the becquerel (1 Ci = 3.7 × 10¹⁰ Bq). It is always written lowercase except at the start of a sentence. The plural is simply 'curies'.
Easily confused with curie
A curio is a rare or unusual object of interest, while a curie is a unit for measuring radioactivity.
Curium is a synthetic radioactive chemical element named after Marie and Pierre Curie, whereas the curie is a unit of radioactivity named after Pierre Curie.