MeSH definition : Atomic species differing in mass number but having the same atomic number. (Grant
& Hackh's Chemical Dictionary, 5th ed);
MeSH synonym : Isotope;
MeSH annotation : for stable isotopes only; GEN: avoid as IM; NIM as coord; Manual 25.20 ; m for metastable
RADIOISOTOPES or specific pre-coord radioisotope; for stable isotopes only; general or unspecified; prefer specifics; m for metastable
equals RADIOISOTOPES or specific pre-coordinated radioisotope;
Wikipedia link : https://en.wikipedia.org/wiki/Isotope;