definition of a radioisotope
1. radioisotope-a radioactive isotope of an element; produced either naturally or artificially. tracer - (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes.isotope-one of two or more atoms with the same atomic number but with different numbers of neutrons.. radioisotope-a radioactive isotope of an element; produced either naturally or artificially. tracer - (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes.