Translation guide
The English word 'isotope' refers to variants of a chemical element with the same number of protons but different numbers of neutrons. In Japanese, the concept is expressed with the scientific term 同位体 (どういたい), which is the standard translation. This guide covers how to talk about isotopes in scientific and everyday contexts.
Referring to isotopes in chemistry, physics, or general science contexts.
The standard Japanese word for 'isotope'. Used in all scientific and technical contexts.
炭素の同位体には、炭素12、炭素13、炭素14がある。
Carbon isotopes include carbon-12, carbon-13, and carbon-14.
同位体比を測定することで、年代を推定できる。
By measuring isotope ratios, we can estimate the age.
The loanword from English, used in some contexts, especially in compound terms or when emphasizing the English origin. Less common than 同位体 in formal writing.
放射性アイソトープは医療に利用される。
Radioactive isotopes are used in medicine.
Specifically referring to unstable isotopes that undergo radioactive decay.
The standard term for 'radioactive isotope'. Used in science, medicine, and environmental contexts.
放射性同位体の半減期は元素によって異なる。
The half-life of radioactive isotopes varies by element.
Referring to isotopes that do not undergo radioactive decay.
The standard term for 'stable isotope'. Used in geochemistry, ecology, and other sciences.
安定同位体分析は生態学でよく使われる。
Stable isotope analysis is often used in ecology.
In formal scientific writing and education, 同位体 is strongly preferred. アイソトープ is more common in casual or industry contexts, or when part of a compound like ラジオアイソトープ. When in doubt, use 同位体.
Abbreviated loanword for 'radioisotope', common in technical and medical fields.
ラジオアイソトープを用いた検査が行われた。
A test using radioisotopes was conducted.