noun
Technical term in physics and chemistry. Refers to atoms of the same element with different numbers of neutrons.
炭素の同位体には、炭素12と炭素14がある。
Carbon isotopes include carbon-12 and carbon-14.
Compound of 同位 (same position, i.e., same place in the periodic table) + 体 (body, substance). A calque from English 'isotope'.